P Chapellier

P Lavenus

B Dulmet

Keywords: Quartz resonator, DRIE, Time & Frequency, MEMS oscillator

In this paper, high quality factor two dimensional length-extension mode (2D-LEM) quartz resonator showing promising performances for Time & Frequency (T&F) applications are reported. They combine the intrinsic qualities of quartz (high Q, low temperature sensitivity and piezoelectricity) and the advantages of silicon resonators: small dimensions, low power consumption and collective processes. Several processes have been investigated as well as several sizes and designs of resonators. A high quality factor (Q), exceeding 200 000, two dimensional length-extension mode (2D-LEM) quartz resonator vibrating at 2.2 and 3 MHz

Fig. 2. Electrode scheme for the actuation of the extension mode of a Quartz Z-cut beam oriented along the Y axis.Ideally, the electrodes should be deposited on both face to optimize the electric field along X-. Real electrode system on the right.

A High Q 2D-Length Extension Mode Resonator for potential Time-Frequency applications I. INTRODUCTION

A three dimensional Length-Extension Mode (3D-LEM) quartz resonator were designed and developed in previous work [START_REF] Le Traon | A Micro-Resonator for Fundamental Physics Experiments and its Possible Interest for Time and Frequency Applications[END_REF] in order to reach quantum ground state. It successfully exhibited a very high Q of 2 000 000 at 4.0 MHz, reaching a Q.f product of 8.10 12 near the theoretical limit of quartz of 3.2.10 13 due to Akiezher losses [START_REF] Ghaffari | Quantum limit of quality factor in silicon micro and nano mechanical resonators[END_REF]. This LEM resonator design could be a potential candidate for time & frequency applications.

Unfortunately, the resonator is quite bulky (1x1x0.5 cm 3 ) and its 3D design does not allow electrical actuation. To overcome these issues, compact planar two dimensional lengthextension mode (2D-LEM) resonators using similar working principle have been developed. In this paper, two types of 2D-LEM resonators , denoted type I and type II, are studied.

II. RESONATORS DESIGN AND QUALITY FACTOR

A. Mode of interest

2D-LEM resonators of type I and II consist of a beam vibrating in extension-compression. The resonant frequency is around a few MHz with a central beam of few millimeters. More precisely, the fundamental mode (n=0) and harmonics [START_REF] Dinger | A minature quartz resonator vibrating at 1 MHz[END_REF] for Z-cut quartz are given by equation ( 1):

𝑓 2𝑛+1 = (2𝑛 + 1) 2.72 𝐿 𝑀𝐻𝑧 ( 1
)
where L is the total length of the vibrating beam in mm and 𝑛 is the mode number. As seen from ( 1), the resonant frequency can be adjusted depending on the targeted applications by varying 𝐿. This should be done though homothetic transformations of the whole structure to maintain the optimized decoupling between the beam and the mounting area. For the ease of processing, resonators are actuated via gold electrodes only deposited on the upper surface. The electric field is generated along X-axis while the engendered beam displacement occurs along Y-axis as it can been seen in Fig. 2.

B. Resonators designs 1) First design, "type I" resonator

In addition to the central beam, the type I resonator has two large lateral beams that vibrate in an in-plane forced flexure movement that compensates for the shear stress induced though the Poisson effect by the vibrating central beam. Thus, the confinement of the stress close to the central beam allows minimized deformation in the mounting area, leading to a high intrinsic quality factor.

Central beam

Lateral beam

Links

Mounting areas

The deformation mode of the type I resonator obtained with Finite Element Method simulations (FEM) is shown in Fig. 3.

2) Second design, "type II" resonator

In addition to the central beam, the type II resonator has two thin lateral beams. The decoupling between the central beam and the mounting area is partly ensured by a flexure movement similar to the type I resonator. This is illustrated in Fig. 4 (left) which shows the magnified deformation along X axis of the type II 2D-LEM resonator. The type II 2D-LEM resonator also benefits from an additional compensation mechanism relying on an length-extension vibration of the lateral beam in opposite phase in comparison to the central beam as shown in Fig. 4 (right). This figure shows the magnified deformation along Y axis.

C. Quality factor

The quality factor of a resonator can be defined as the ratio of the stored energy over the energy dissipated per cycle via different damping mechanisms. It can be written under vacuum as:

1 𝑄 = 1 𝑄 𝑣𝑖𝑠𝑐 + 1 𝑄 𝐴𝐾𝐸 + 1 𝑄 𝑇𝐸𝐷 + 1 𝑄 𝑎𝑛𝑐ℎ𝑜𝑟
where damping mecanisms are briefly described in Table I. In the 2D-LEM case, a more complete description can be found in [START_REF] Brand | Resonant MEMS-Fundamentals, Implementation and Application, First Edit[END_REF]. From the FEM simulations a quality factor around 600 000 is expected for resonators vibrating at a few MHz making possible to reach a Q.f product between 1,2 and 1,5.10 12 Hz. Q.f depends on the material. For quartz, the limit is 3,2.10 13 Hz. For a vibrating structure at few MHz, QAKE~10 7 Qvisc Arises from the viscosity of the gold from the electrodes.

Analytical model has been developed in [START_REF] Bourgeteau-Verlhac | Gold Thin Film Viscoelastic Losses of a Length Extension Mode Resonator[END_REF]. The model depends on the ratio of the vibrating thickness of quartz and gold as well as the resonant frequency. Qvisc=6,1.10 5 at 3 MHz and 5,7.10 5 at 2.2 MHz III. PROCESS FLOW Standard wet etching using hydrofluoric acid (HF) is not suited for etching the vibrating part due to its high anisotropy and faceting [START_REF] Pelle | Etch rates of crystallographic planes in Z -cut quartzexperiments and simulation[END_REF]. Deep Reactive Ion Etching of quartz has been developed for the last decade thanks to the development of high density plasma etcher. Resonators using DRIE have been reported [START_REF] Boy | Collective fabrication of 20 MHz resonators by deep Reactive Ion Etching on 3" quartz wafers[END_REF][9] but vertical etching quartz over several tens to hundred microns is still challenging. In the present study, two process flows has been used and compared.

A. Process 1: Two DRIE steps process

Process 1 is described in Fig. 5. and uses two DRIE steps: once the patterns of the resonators are made with the first This DRIE process uses a combination of a fluorocarbon gas (CF4) and dioxygen: vertical etching of quartz takes place thanks to the presence of a passivating polymer [START_REF] Sankaran | Integrated feature scale modeling of plasma processing of porous and solid SiO2. I. Fluorocarbon etching[END_REF] on the sidewall.

This process suffers from a major issue : the wafer is craking due to the release of the stress induced by DRIE heating as shown in the Fig. 6., This phenomon has been observed in previous work [START_REF] Boy | Collective fabrication of 20 MHz resonators by deep Reactive Ion Etching on 3" quartz wafers[END_REF].

B. Process 2: One DRIE step process with cavities etched by wet chemical solution

To reduce the craking, a process with reduced duration of the DRIE steps has been tested and is presented in Fig. 7 : in this case, the cavities were etched with a wet chemical solution HF-NH4F has been developed and . Chromium/Gold layers are evaporated on both faces as they serve as electrodes and etching mask during the wet chemical etching step. Only the back side of the vibrating part is rough as the release of the structure is made by the DRIE step.

IV. RESULTS & DISCUSSION

A. Results of process 1 1) Measurements

Resonators vibrating at 3.0 and 2.2 MHz have been manufactured (Fig. 8) and electrical measurements were performed under vacuum (10 -4 mbar) with impedance analyser (Keysight EA990A) and are given in table 2 with others works on similar devices. Fits are obtained with a standard Butterwoth-Van Dyke model (BVD). Simulated frequency, theoretical values and experimental values are in very good agreement.Experimental quality factors as high as 180 000 for type II resonators vibrating at 2.2 MHz was found but these are still half of the value that is expected from FEM simulations, meaning that one or more damping mechanism has been underestimated or wrongly neglected.

2) Analysis of the measured quality factors

One significant difference between the real structure and the simulated one lies in the sidewalls angle : DRIE leads to not perfectly vertical sidewalls as illustrated in Fig. 9. New FEM simulations have been carried out to estimate how this non verticality modify the losses in the mounting areas (Qanchor).FEM simulations give us the dependency of the Qanchor versus sidewall angle in Fig. 9. It appears that energy trapping in the vibrating part becomes rapidly less efficient with an, even slightly, non-vertical sidewall angle. For an angle around 3° which is reachable with the current process 1, Qanchor fells down around 400 000 for the 3 MHz resonator as shown in Fig. 9 and 500 000 for the 2.2 MHz and explains the experimental values.

B. Results of process 2

The craking with the process 2 was reduced but resonators shown lower performances as Q did not exceed 130 000 at 3 MHz and type II resonators showed better performances. The degraded quality factors are probably due the presence of the pyramids resulting from the wet etching of the cavities on the back side as illustrated in Fig 10 . As there are no pyramids on the top face, the structure obtained with process 2 is less symmetrical than in the case of process 1, which may amplify the loss energy through the anchors and degrade Qanchor hence the overall decrease of the experimental Q.

Table 2 shows the results of the different processes and designs used as well as previous work on resonators using the same mode of interest, Rm is the serie resistance in the standard BVD model. One can note that the larger resonators (with lower resonant frequencies) present better performances than the smaller ones (higher resonant frequencies) and that was also observed in the work of Kawashima. Also, type II resonators have shown better perfomances than equivalent previous standard type I design which seems to indicate a more efficient design with the out of phase extension-compression mode of the lateral beams.

V. CONCLUSIONS

In this paper, new 2D-LEM quartz resonators with potential T&F applications have been demonstrated with first prototypes showing encouraging electro-mechanical characteristics providing a Q.f product near 10 12 Hz. The two main limiting damping mecanisms have been identified: the energy loses arise on one hand from the the viscous dissipation in the gold layer forming the electrodes and on the other hand from the energy dissipation in the mounting areas. The latter one is amplified due to the slightly non vertical sidewall as well as from the surface rugosity induced the chemical wet etching of the cavities. Future work will be focused on improving the quality factor by tackling the aforementioned damping source.

Fig. 1 .

 1 Fig. 1. a) Concept of the 3D-LEM: a ring around the pillar with an out of phase length-extension vibration, b) 1.5-inches square quartz wafer including 9 3D-LEM made using wet etching, c) detail of the micropillar.

Fig. 3 .

 3 Fig. 3. Amplified nodal displacements of the central beam of a type I resonator during its length-extension mode vibration.

Fig. 4 .

 4 Fig. 4. Type II 2D-LEM resonator vibrating mode. On the left, the X component of the magnified deformation showing flexure movement in thelateral beams. On the right, the Y predominant extension out-of-phase component of the deformation of pillar and lateral beams.

  QTED>107 in the case of the 2D-LEM because there is no flexion of the central pillar.

Fig. 5

 5 Fig. 5 Process flow 1 using two DRIE steps.

Fig. 8 .

 8 Fig. 8. Right, top line type I resonators vibrating at 2.2 MHz, bottom line at 3 MHz. Left, focus on a 3 MHz resonator.

Fig. 7 Fig. 6 .

 76 Fig. 7 Process flow 3 using wet etching to create cavities and one DRIE step on top face. Etching gas is the same as in process 2.

Fig. 9 .

 9 Fig. 9. Simulations using FEM of the Qanchor vs sidewall angle for a 3 MHz type I resonator. In detail, scanning electron microscopy (SEM) of a 90 µm deep cross section beam.

Fig. 10 .

 10 Fig. 10. Left: Schemes of the cross beam section etched with both processes. Right: photography of the back side of a resonator using wet etching and presence of pyramids with several tens of microns diameters.

Table 1 . Summary of the damping mecanims and estimations in the 2D- LEM case. Notation Damping source Model and estimation in the 2D-LEM case

 1

		Strain energy that	Simulations using Finite Element
	Qanchor	leaks at the anchors (i.e. mounting	Method (FEM) By design Qanchor>10 8 for perfect
		areas)			geometry
		Thermoeslatiscity
		damping is the
		energy loss due the
		bending of the
		resonator: creation
	QTED	of	a	thermal
		gradient	where
		there is a strain
		gradient leading to
		thermal transport
		and damping.

Table 2 : Experimental Q and Rm of the different types 2D-LEM obtained with the three process of the work and previous works on 2D-LEM. Process Design fres (MHz) Q (10 3 ) Rm (kOhms) Q.f (10 11 Hz)

 2

	1	I II	2.2 3.0 2.2 3.0	135 110 180 150	7.8 11 5.4 7.5	3.0 3.3 4.0 4.5
			2.2	102	11	2.2
		I	3.0	98	11.3	2.9
	2		4.5	85	14.6	3.8
		II	3.0 4.5	129 117	8.5 9.8	3.9 5.3
	Dinger [3]	1.0	200	2.5	2.0
			1.5	350	0.28	5.2
	Kawashima [12]	1.2	370	0.26	4.4
			1.1	430	0.31	4.7

ACKNOWLEDGMENT

This work is founded by the Centre National d'Etudes Spatiales CNES.


Primavera De Filippi

Citizenship in the Era of Blockchain-Based Virtual Nations

Introduction

In the last decades, modern democracies have been witnessing a low rate of political participation and civic engagement with existing governmental institutions. Low voter turnout, especially with younger generations, is raising significant concerns for many representative democracies and trust in public institutions has dropped to a point that it has become difficult for people to engage in political activity. 1Civic participation is not dead, however, it is only shifting to a new space. With the advent of Internet and digital technologies, citizens of the world are coalescing into increasingly globalised social movements [START_REF] Cohen | Global social movements[END_REF], paving the way for new forms of political engagement (Della Porta & Tarrow 2005). With the blockchain, these individuals could find new ways to spontaneously organise and coordinate themselves into transnational "cloud communities" and-as Liav Orgad suggests-even acquire their own self-sovereign identity that subsists independently of any nation-state. Those, I believe, are some of the most compelling developments of blockchain technology, which I have been following closely over the past few years. But what makes blockchain technology a powerful tool for promoting disintermediation and decentralised coordination-i.e. a trustless technology-also constitute one of its greatest limitations, especially when it comes to political deliberation. While politics is about reaching a compromise between conflicting interests and values, blockchain technology operates via distributed consensus and an exit-based conflict resolution system. As underlined by Rainer Bauböck , relying on voluntary cloud communities as a means to govern society could significantly increase inequalities, leading to an overall loss of democratic representation and wealth redistribution. In a sense, I agree with both Orgad and Bauböck . When brought to an extreme, blockchain technology could create-simultaneously-a utopian society characterised by greater individual freedom and autonomy, and a dystopian society driven by market-based incentives and self-dealing. But reality is neither black or white; it often has many different shades of gray. I see blockchain technology as neither the cure nor the curse of today's political issues. Rather, I see it as a tool that could enable us to experiment with new governance structures and alternative political systems-in a world where there is very little room left for experimentation.

Multiple shades of activism

Digital activism is a not a recent phenomenon. Social movements increasingly leverage the power of digital technologies to coordinate themselves and communicate to a broader audience-as illustrated by the role played by social media during the Arab uprisings in 2011 [START_REF] Howard | Opening closed regimes: what was the role of social media during the Arab Spring?[END_REF]. But the Internet also enabled the emergence of new communities of kinship, with a variety of online platforms (e.g Facebook, Twitter, Whatsapp ) gathering people around specific interests or values, regardless of their political views. Some of these communities operate as tight social groups, providing members with a newfound sense of belonging and a collective identity [START_REF] Wellman | Virtual communities as communities[END_REF]. While they do not engage in what we usually regard as political activity, these online communities play a key role in shaping how people organise and coordinate themselves, in ways that significantly differ from those of existing political institutions [START_REF] Norris | The bridging and bonding role of online communities[END_REF]. Apart from the legal regime these communities operate with, they are governed by their own systems of rules and social norms-which members voluntary abide by. In her book, "Social Movements and Their Technologies: Wiring Social Change", Stefania Milan illustrates the different approaches of social movements in materialising their ideas into the world [START_REF] Milan | Social movements and their technologies: Wiring social change[END_REF]. Insiders adopt a cooperative attitude: they recognise existing institutions as a legitimate source of power and actively engage in their game, through advocacy and traditional decision-making procedures [START_REF] Moe | Power and political institutions[END_REF]. Outsiders adopt a more confrontational attitude: they reject the rules of these institutions and choose instead to exert pressure from the outside, through campaigns, protest or other form of political resistance [START_REF] Maloney | Interest groups and public policy: the insider/outsider model revisited[END_REF]. Finally, what she refers to as beyonders are a wholly different bunch. Beyonders simply refuse to engage with existing institutions: they do not want to fight them nor do they want to change them, they simply regard them as a leftover from a past era-which they are trying to render obsolete by building new systems [START_REF] Hintz | User rights for the Internet age: Communications policy according to "Netizens[END_REF]. Thus, relatively to the other two groups, beyonders operate in a way that is more autonomous or independent; they do not play for or against the established political system, they just decide to ignore it or bypass it. Is it fair to conclude that beyonders do not play a political role in society? Clearly not. By creating an alternative to existing institutions, they exert an indirect pressure forcing them to adjust themselves to maintain their position. Perhaps more so than insiders and outsiders , who operate within a given political framework, beyonders are deeply concerned with social change. Their political action is the result of a constructive reaction to the current state of affairs. They are responding to their own needs using new schemes and methodologies, leveraging the power of communities to create new institutions that will help them fulfill their missions-through what essentially amounts to a new form of political organisation.

Beyond the blockchain

Today, in the shadow corners of the Internet, a new group of beyonders is emerging, looking at blockchain technology as a means to replace many of our traditional institutions. While most of the attention was put, initially, on Bitcoin disrupting banks and other financial operators (De Filippi 2014), as people understood the full potential of blockchain technology, they saw it a means to implement new governance structures that could potentially replace some of our existing systems of governance [START_REF] Davidson | Disrupting governance: The new institutional economics of distributed ledger technology[END_REF].

At the extreme end of this spectrum are those who envision the creation of new blockchain-based virtual nations, with a view to ultimately replace the nation-state. This is the case, for instance, of Bitnation : an initiative aimed at creating a new sovereign jurisdiction that operates only and exclusively in cyberspace, independently of any geographical boundaries. Founded in 2014, Bitnation describes itself as a decentralized borderless voluntary nation that anyone can join or leave as they wish: a transnational 2 community of global citizens that spontaneously coordinate themselves, with no recourse to coercion. To early Internet pioneers, this might sound familiar. Already in 1996, in the "Declaration of the Independence of Cyberspace", John Perry Barlow described the digital world as an independent space that simply could not be regulated, because-he claimed-governments did not have the right nor the capacity to exert their sovereignty over it (even though history has eventually taught us otherwise).

3 Barlow was essentially a beyonder -mocking the various governmental attempts at regulating the Internet landscape, in ways that he considered to be ineffective in this new digital era. Similarly, Bitnation is mostly the result of a beyonders ' approach to governance, trying to create a new sovereign nation that ignores the rules and procedures of existing nation-states, regarded as obsolete in this new digital world. Because it operates on a transnational and decentralised peer-to-peer network (the Ethereum blockchain), Bitnation is not under the control of any one government. Indeed, by relying on blockchain technology, Bitnation is creating a system that not only tries to escape from the hegemony of nation-states-because it has no single point of failure, or control-but also tries to compete with existing institutions and governmental systems-by providing self-sovereign identities, notarisation services, property rights and company registration, dispute resolution systems, etc. which are usually associated with the functions of the public administration. The Ethereum blockchain is particularly useful in this context, because-as a public and transnational blockchain-it provides the necessary transparency, verifiability, incorruptibility and trust that one would expect from these governmental services. " Governance in the real world is so fucked. We have to start thinking about how to build it in the virtual world " said Lawrence Lessig in an interview , after he resigned from the 2016 presidential campaign. While Lessig was referring to the creation of a massive multiplayer online game inviting players to experiment with different forms of governances, it might be worth investigating whether initiatives such as Bitnation, and other attempts at creating blockchain-based virtual nations (such as Cultu.re) or even blockchain-based virtual worlds (such as Decentraland ) could actually provide a new space of experimentation, allowing people to experiment with new political systems that operate outside of any defined territory. Indeed, these initiatives-which rely on decentralised blockchain-based systems-are not located in any given jurisdiction: they subsist in a transnational space, which has yet to be colonised by new governance structures and experimental political regimes.

Blockchain-based virtual nations

2 According to the Bitnation website, Bitnation is fostering "a peer-to-peer voluntary governance system, rather than the current 'top-down', 'one-size-fits-all' model, restrained by the current geographical apartheid, where your quality of life is defined by where you were arbitrarily born." See https://bitnation.co/join-the-team/ 3 " Governments of the Industrial World, you weary giants of flesh and steel, I come from Cyberspace, the new home of Mind. On behalf of the future, I ask you of the past to leave us alone. You are not welcome among us. You have no sovereignty where we gather " [START_REF] Barlow | Declaration of Independence of Cyberspace[END_REF].

or nation-state, but to a global community that transcends national boundaries? Can they support a new 5 understanding of citizenship as collective identity, providing new opportunities for collective action and civic participation in a post-national world [START_REF] Sassen | Towards post-national and denationalized citizenship[END_REF])? As with many things today, the answer is not a simple one. The concept of blockchain-based virtual nations is interesting because it is highly controversial. It is, in fact, supported by different groups, for very different purposes. On the one hand, the concept of a virtual nation is appealing to many libertarians, who see it as an opportunity to reduce the room for governmental intervention, by creating new ad-hoc governmental structures aimed at creating a society governed by (unregulated) market forces, and nothing else. This is the vision brought forward most prominently by Peter Thiel, who envisions the creation of a new sovereign nation on an offshore artificial island , built 200 miles off the Californian coast. This vision is also shared by a number of crypto-libertarians [START_REF] May | Crypto anarchy and virtual communities[END_REF], such as the team behind Bitnation , who believe that-since we have lost trust in our governments-we shall now rely on blockchain technology to create trustless systems ( i.e. systems where trust is no longer needed) with a view to support and facilitate a series of atomic peer-to-peer interactions in a seemingly stateless environment [START_REF] Atzori | Blockchain technology and decentralized governance: Is the state still necessary? Working Paper[END_REF]. On the other hand, there are people who see virtual nations as an opportunity to overcome the lack of trust in governmental institutions, through the creation of new trusted communities with a global scope. These communities can experiment with new institutional structures that operate independently from, or as a complement to existing institutions. They can support the emergence of grassroots initiatives designed to fill the gaps generated by the progressive shrinking of the welfare state [START_REF] Feigenbaum | Shrinking the state: The political underpinnings of privatization[END_REF])-i.e. the provision of public services and shared infrastructure, the pursuit of the common good, and the protection of individual and collective rights. Blockchain technologies could provide new mechanisms of social or political coordination, allowing for transnational communities and activist groups (such as human rights defenders, Internet freedoms advocates and climate change campaigners) to gather around a newfound sense of identity and organise themselves as a collective. The idea is not to replace nation-states with new or competing forms of sovereignty, but rather to provide new means for global communities to mobilise and experiment with new ways of engaging in civic life. If political participation no longer finds its place in the context of traditional governmental structures, perhaps these virtual communities-or cloud communities , as Orgad calls them-might be able to bring civics back to life. Indeed, if citizenship refers not only to a legal status, but also to an individual's political activity [START_REF] Dalton | Citizenship norms and the expansion of political participation[END_REF]) and collective identity [START_REF] Eisenstadt | The construction of collective identity[END_REF], we might soon witness the emergence of new global citizens, who regard these new virtual nations as polities and self-identify as their members. This is the vision supported by initiatives like Democracy Earth and Aragon , two blockchain-based platforms providing tools for small and large organisations to operate in a globalised post nation-state world, through their own governance rules and dispute resolution systems. Without trying to replace the role of the state as a political institution, these initiatives are exploring whether (and how) some of the functions undertaken by governmental authorities-e .g. the issuance of identity cards, recordation of vital records and maintenance of public registries, etc.-could be transposed into a blockchain-based system. People are thus ideally free to decide, on a case-by-case basis, whether they want to rely on traditional institutions and governmental frameworks, or whether they would rather adopt these new experimental systems, whose values they might feel more attuned with. As a general rule, citizens cannot easily revoke their allegiance to a particular nation-state, because-as highlighted by Rainer Bauböck -the social contract described by Hobbes and Rousseau is not a negotiable contractual agreement entered into by consent ( i.e. citizenship as a legal status is generally something that one does not chose and that, once acquired, cannot be easily gotten ridden of). Yet, to the extent possible, they could choose to acquire additional citizenships, becoming members of multiple communities based on affinity and consent. Insofar as they provide valuable services to their citizens, these virtual communities (or virtual nations ) may be competing with one another-and potentially with nation-states-so as to expand their user-base. While this might sound speculative at best, we are already seeing glimmers of this world. For several years, the republic of Estonia has been trying to create a "digital nation for global citizens," as illustrated 6 by its e-residency program, which provides a government-issued digital ID to all individuals requesting it. Inspired by the notion of government as a platform (O'Reilly 2011), e-Estonia is trying to become the hub for every governmental service, providing all of its electronic residents with a secure identification system, notarisation services, and even the ability to run a company or open a bank account, without ever putting foot into Estonia. With over 28,000 e-residents from all over the world, today, the state of Estonia increasingly operates on a digital layer, enabling people to interact with its governmental platform independently of their country of citizenship or residency.7

Competing sovereignties

Competition between nation-states, trying to collect new members by providing more efficient or reliable governments services, has, therefore, already begun. If Estonia can collect e-residents on a global scale -in spite of its national boundaries-what would prevent virtual nations from doing the same, without a physical territory? Are we actually moving towards a world in which multiple nations are competing to attract more citizens, in the same way as companies are today competing to attract more customers?8 Of course, things get murky when we move from purely administrative tasks-like identity, property and company recordation-to more political tasks, involving policy and decision-making. If people could choose to become citizens only of the communities with whom they agree, they would essentially engage in a generalised version of nation-shopping, constantly trying to find the jurisdictions that seem the most advantageous for them. When brought to an extreme, this would ultimately mean the end of politics.

Politics is all about compromises, in order to accommodate different viewpoints without entering into a conflict. An opt-in or exit-based political system essentially eliminates the notion of politics, because it removes the need for compromise. People with different values or opinions would no longer need to argue and deliberate in order to reach consensus, because if they're in disagreement, they can simply leave.

As Bauböck recognises, there are significant challenges in letting people choose which nation they want to pledge allegiance to. The state as a sovereign entity-Hobbes' Leviathan -is not only responsible for preserving the public order, it is also in charge of promoting the general interests, producing common goods and creating a collective sense of redistribution and justice. All these functions could disappear as we move towards a more market-based approach to citizenship. I am, however, more pessimistic than Bauböck when it comes to the way nation-states will adapt to these technological changes. Given the progressive disengagement of citizens in local politics, and the growing distrust in existing institutions-whose legitimacy is increasingly put into question-it might not be surprising to see a new wave of nationalism emerging all over the world, with nation-states drawing on nationalist and anti-immigration narratives to reinforce their hegemony over the territory, essentially redefining ongoing relationships between citizens and non-citizens [START_REF] Mitchell | Transnational discourse: bringing geography back in[END_REF]. At the same time, due to the increasing trends towards globalisation, large Internet corporations, like Google or Facebook, are progressively taking on some of the functions that were once specific to the nation-state: from the task of supporting the discourses in the public sphere [START_REF] Habermas | The structural transformation of the public sphere: An inquiry into a category of bourgeois society[END_REF] to the role of acting as identity providers. With several billions of users on their platforms, these corporations are slowly turning into de facto corporate nations, with their own system of rules that they unilaterally define and impose on their "citizens". Traditional nation-states might, therefore, soon have to compete not only with virtual nations, but also with these new transnational corporate nations-similar to Neal Stephenson's franchulates as science-fiction fans will certainly point out [START_REF] Stephenson | Snow crash[END_REF].

New opportunities for experimentation

It is in this convoluted (and daunting) context that I see the rise of blockchain-based virtual nations as a positive omen. Perhaps the reference to virtual nation s is not the most accurate one, because the term has a strong political connotation and somewhat gives the impression that these communities are assuming the role of traditional nation-states. While some of them do intend to replace the figure of the nation-state (e.g. Bitnation), others are simply trying to experiment with new and allegedly apolitical governance systems [START_REF] Atzori | Blockchain technology and decentralized governance: Is the state still necessary? Working Paper[END_REF], which nevertheless play a crucial political function. Because they rely on voluntary association, virtual communities might well remove the need for compromises within a single community, yet they do not eliminate the need for compromise between multiple communities. Hence, politics are not gone, they are simply moving into a different layer. By aggregating people with similar values and opinions, these virtual communities could in fact strengthen the voice of certain minorities-usually stifled by the majority's opinion-and create a more lively debate and political discourse at the outside (rather than on the inside) of these communities. As such, they could end up participating in conventional politics, along with other real-world interests groups. To conclude, let me take the stance of a beyonder for a moment. As a member of Creative Commons, I 9 have always been fascinated by its solution. Instead of trying to reform copyright law from the inside or fight it from the outside, Creative Commons introduced an alternative legal regime for creative works that coexists with the existing regulatory framework (in fact, it is based on it) for authors to experiment with new business models that do not rely on the exclusivity and artificial scarcity of copyright law.

Today, with the advent of blockchain technologies, a new wave of innovation is underway in the realm of governance. This innovation is one that will benefit everyone: the insiders , i.e. governmental authorities like Estonia, relying on blockchain technology to increase the transparency and accountability of public administrations; the outsiders , like Peter Thiel, trying to create new self-sovereign nations with the intention to escape from the laws and control of existing nation-states; and, of course, the beyonders , like Bitnation et al., eager to use the technology to support the coordination of transnational communities of voluntary association that operate independently of traditional nation-states, but are capable of peacefully coexisting with them. It is the latter which I am the most excited about, and which I believe could contribute to developing new governance models that might help us build a real global democracy.

According to Pew Research, in

2016, only 19% of Americans said they trust their government, among the lowest levels in the past half-century. See http://www.people-press.org/2015/11/23/beyond-distrust-how-americans-view-their-government/ . The same is true at the international level. A GCF survey found out that 85% of the respondents in eight countries believe that the UN needs to be reformed to better deal with global risks and 71% support the establishment of a new supranational organisation. See https://api.globalchallenges.org/static/files/ComRes.pdf

The notion of "world citizen" has been endorsed by a variety of scholars, activists and social movements. See, in particular, Ulrich Beck's notion of "cosmopolitanism" and discussions on the "post-Westphalian" international system[START_REF] Beck | Toward a new critical theory with a cosmopolitan intent[END_REF][START_REF] Beck | Unpacking cosmopolitanism for the social sciences: a research agenda[END_REF].

See also the work ofToloyan (1996),[START_REF] Grewal | Transnational America: feminisms, diasporas, neoliberalisms[END_REF] and Van Hear (2005) on diasporas as transnational entities.

" E-Residency is a new digital nation for global citizens, powered by the Republic of Estonia. " See https://e-resident.gov.ee/

According to Taavi Kotka, Chief Innovation Officer of Estonia since 2013: " Countries are like enterprises. They want to increase the wealth of their own people ."[START_REF] Heller | Estonia, the Digital Republic[END_REF]

According to its website: " Bitnation is creating a new world where thousands or millions of nations actually compete for customers by providing better services, instead of using force. It's a world where everyone can chose ." See http://bitnation.co

Creative Commons is an organisation devoted to expanding the range of artistic, academic, and other content available for people to share and build upon. See http://creativecommons.org


Bitcoin by Primavera De Filippi in Haunter D. & Op den Kamp C. (eds). A History of Intellectual Property in 50 Objects. Cambridge University Press

On 12 January 2009 a pseudonymous entity signed a transaction that instructed a distributed network to transfer a small amount of digital currency to Hal Finney, one of the key figures of the cypherpunk movement. After a few minutes, the transaction was recorded on a distributed public ledger, permanently updating the balance of both parties. This transaction-the first Bitcoin transaction-marked the beginning of a new era of decentralized payment systems, ushering in a variety of new financial services that do not depend on any centralized clearinghouse or other financial middleman.

Bitcoin is regarded by many as a powerful technological innovation that could disrupt many sectors of activities, in the realm of finance and beyond. But the underlying technology on which the network operates, the Bitcoin blockchain can do much more than that. Just as the internet did in the early-'90s, blockchain technology carries with it a whole new range of promises concerning how decentralization can support and promote individual freedoms and autonomy. Blockchain proponents believe that Bitcoin and other cryptocurrency platforms will revolutionize mechanisms of value exchange in the same way that the internet transformed information sharing, by providing a platform for people to exchange digital resources, in a secure and decentralized manner, without the need to rely on any intermediary operator or trusted authority.

A blockchain is a decentralized database of transactions maintained by a distributed network of computers, which all contribute to the verification and the validation of transactions. Once accepted, these transactions are recorded inside a "block" of transactions, which incorporates a reference to the previous blocks. This creates a long chain of blocks -a "blockchain"-that stores the whole history of transactions in a chronological order. Every block contains information about a particular set of transactions, a reference to the preceding block in the blockchain, and the answer to a complex mathematical puzzle, which is used to validate the data associated with that block. A copy of the blockchain is stored on every computer in the network, making it virtually impossible for anyone to unilaterally modify the data stored on this decentralized database, because if anyone tries to modify even a single of these transactions, the fraud will be immediately detected by all other network participants. The initial implementation of the idea of a blockchain is found in the first Bitcoin whitepaper. Released on 31 October 2008, it was attributed to "Satoshi Nakamoto," a pseudonymous entity who has managed to keep his or her (or their) identity secret despite numerous attempts by the media to unravel this secret identity.

While no one owns the Bitcoin network, many people own Bitcoins, the virtual currency that enables this network to run and operate in an open and distributed manner. But what does it mean to "own" a Bitcoin? With cash, things are relatively simple: if you have a $10 bill in your wallet, you probably own it: as with many physical things, ownership is closely related to possession. Ownership of digital things is much more complicated, not because possession is more difficult to assess-it is relatively straightforward to determine whether or not I have a digital file stored on my device-but because in the digital world possession doesn't really line up neatly with ownership. I might possess a copy of an MP3 sound recording, but I may not have purchased it and even if I have it's not clear that I "own" it.

Intellectual property is a legal layer of artificial scarcity imposed over specific types of information, in order to facilitate the trading of these information goods. Its goal was to re-align the properties of information (a non-rival good) with the properties of the medium into which it had been embodied (a physical and therefore necessarily rival good). The model broke down with the advent of Internet and digital technologies. Digital resources are-just like information-inherently non-rival: they can be held and consumed by multiple persons at the same time, without this affecting the opportunities for others to enjoy the same resource. The non-rivalry of the digital world is one of the wonders of the information age, and is fundamental to our ability to use the internet in order to share knowledge with one another. It also lies at the heart of the battles that have been waged over intellectual property in the digital age.

From the late 1990s and early 2000s, there emerged a growing wave of copyright infringement-sometimes called "online piracy"-where millions of copyrighted songs, videos and audiobooks were illegitimately reproduced and distributed over the internet. The pushback from the content industries led to lawsuits, new laws, and earnest public service announcements, along with a drop in the general perception of the legitimacy of copyright law in the digital environment. The law was regarded by many digital natives as a leftover from a previous era, or simply something that could be safely ignored.

Solving the digital scarcity problem is at the core of Bitcoin. Although a Bitcoin is nothing more than a series of bits stored on a decentralized public ledger that is associated with someone's Bitcoin account, because of the design of the underlying blockchain network, no one has the ability to reproduce or multiply their Bitcoin in the same way as they could reproduce a digital file. With the blockchain, we have gained the ability to create digital resources that are inherently scarce, in that they cannot be digitally copied or reproduced. Before, it was only possible to reproduce digital assets, since transferring a digital file over the internet still allows the original owner to keep a copy of the file. With Bitcoin, it is now possible to transfer digital assets, without copying them.. The development of Bitcoin thus marked the beginning of a new era: an era of digital scarcity, one where digital bits can be transferred over the internet, without losing their scarcity, and without recourse to intellectual property laws. The first great advance ushered in by Bitcoin is therefore that it enables us, for the first time, to apply the notion of property over digital assets. And we're not talking here of intellectual property over an information good, but of a real property right over digital goods.

But the significance of the blockchain is not limited to digital currency. Less than ten years after the first Bitcoin transaction, the blockchain protocol has inspired a large variety of new applications, many of which extend well beyond the realm of finance. From decentralized registries, recordation systems, marketplaces and peer-to-peer value exchanges, the blockchain protocol is currently being used for numerous applications that do not rely on any centralized intermediary or middleman. The blockchain can be used as the underlying transaction layer for the trading of many digital assets in a secure and decentralized manner.

The same rules that apply to the transfer of Bitcoins can be applied to other digital resources-whether these are digital currencies, certificates, copyright licenses, or even titles to specific assets or commodities that subsist in the physical world. It can even be applied to revolutionize trademark law: rather than rely on brands and marks to distinguish the source of goods, companies can rely on a blockchain in order to prove the authenticity of their products, by associating them with a particular Bitcoin transaction. For instance, Armani or Louis Vuitton could transfer a small fraction of Bitcoins along with the purchase of any of their designer clothes, which would serve as a seal of authenticity to prove that these products are, indeed, authentic. When selling these products on the secondary market, the original purchaser would also need to transfer these Bitcoins to the new buyer-who would then be able to prove and verify that the product is not a counterfeit. Initiatives of this kind already exist to prevent the counterfeiting of luxury goods, in markets such as diamonds, for instance. Today, a diamond's authenticity is guaranteed by paper certificates, which can easily be forged. The company Everledger is using the Bitcoin blockchain to register diamonds, along with their unique identifier, that is, a digest of the diamond's features, including its color, clarity, and imperfections. This contributes to increasing the transparency and traceability of diamonds' supply chains, giving people the possibility to trace the movements of these diamonds as they pass from hands to hands.

Most relevant in the context of intellectual property is the use of Bitcoin and other blockchain-based applications to manage the dissemination of artistic works recorded in a digital format, and the transfer of limited editions of these works. It was, until now, impossible to create limited editions of a digital work, since anyone in possession of one of these editions could simply reproduce it into multiple identical copies. By recording the unique identifier of each legitimate copy of a work on the Bitcoin blockchain, the copy can become forever associated with a particular Bitcoin transaction-even if it is only worth a few cents-so that the ownership of that copy can be transferred in a secure and decentralized manner, just like one would make a Bitcoin transaction. Of course, people still retain the ability to reproduce the digital work and distribute it as they wish, but only the recipients of the relevant Bitcoin transactions will be able to prove that they are the legitimate owners of an authorized copy of the work.

This usage of the Bitcoin blockchain offers new opportunities to artists, eager to distribute their digital works over the internet while preserving the scarcity and authenticity of these works. Using the blockchain, digital objects can be imbued with a greater degree of rivalry and may be traded or exchanged in ways that are roughly equivalent to tangible property-i.e. claims to digital copies could be transferred from user to user, just like a book can be passed along from person to person. Secondary markets are likely to emerge, where copyright owners can transfer title to digital resources-e-books, digital movies, music files, and so on-which will potentially lower the price of these resources and increase their public availability.

The Bitcoin blockchain is, therefore, much more than a decentralized payment system. It is a decentralized ledger that makes it possible for anyone to exchange scarce digital resources-such as virtual currencies or unique digital copies of a creative work-in a secure and decentralized manner, without the need to rely on any trusted authority or centralized middleman.

At first glance, Bitcoin might thus appear to be a powerful tool for the enforcement of copyright in the digital world. Yet, Bitcoin's relationship with intellectual property laws is ultimately a double-edged sword. Depending on the usage that is made of the technology, it could serve either as a friend or foe to the intellectual property regime-and copyright law in particular.

Indeed, the very same properties that make Bitcoin so valuable for exchanging value in secure and decentralized manner, also make it a powerful tool to publish and disseminate information in a way that cannot be retroactively deleted or modified by anyone. On the one hand, the Bitcoin blockchain can be, and has been, used by authors and artists to publish and license their works, in ways that might facilitate the enforcement of copyright law. On the other hand, the same technology is providing new means for people to disseminate information on a tamperresistant and censor-resistant network, in ways that might easily run afoul of existing laws aimed at restricting the flow of information.

By recording data on the Bitcoin blockchain, a user can be sure that, as long as the blockchain exists, these data will remain permanently and persistently available to anyone who holds a valid copy of the blockchain. Any attempt by a third party to censor such information will be doomed to failure, since the network will simply ignore the request. The underlying protocol of the Bitcoin network makes it extremely difficult for censorship to occur in the first place, since it requires a coordinated action of more than 51% of the computational power of the network to retroactively alter the blockchain.

Because of the disintermediated nature of a blockchain, law enforcement authorities do not have the ability to restrict the flow of online communications using traditional means. In the context of most centralized online platforms, enforcement authorities can exert pressure on service providers or intermediary operators, who are responsible-upon notice-for taking down any illicit content from their platforms. In a decentralized network like Bitcoin, the lack of a central authority in charge of managing the network makes it virtually impossible for any single party to control the type of information that can be posted onto the network, or subsequently to censor or block that information. Whether it is copyright infringing material, cyber-bullying or hate speech, all information recorded on the Bitcoin blockchain will forever exist, outside the reach of the long arms of the law.

It is the dichotomy between blockchain technology as a regulatory technology and its potential use as an unregulatable technology that makes it so interesting from a legal perspective. The distinctive features of a blockchain-in terms of transparency, resiliency, and incorruptibility-can be regarded simultaneously as the greatest gift and as the greatest curse for intellectual property. While they might strengthen the ability for right holders to enforce their intellectual property rights, they may also lead to the demise of the current copyright regime, as well as other laws aimed at restricting the flow of information. ♦

Further Reading

Primavera De Hal R. Varian (1999). Markets for information goods (Vol. 99). Institute for Monetary and Economic Studies, Bank of Japan

  Filippi and Aaron Wright (2018). Blockchain & The Law: The Rule of Code. Cambridge: Harvard University Press. Primavera De Filippi & Samer Hassan (2016). Blockchain technology as a regulatory technology: From code is law to law is code. First Monday, 21(12) Jessica Litman (2001). Digital copyright. Prometheus books. Satoshi Nakamoto (2008) Bitcoin: A Peer-to-Peer Electronic Cash System. Available at: https://bitcoin.org/bitcoin.pdf Don Tapscott and Alex Tapscott (2016) Blockchain Revolution: How the Technology Behind Bitcoin is Changing Money, Business, and the World. New York: Portfolio Penguin.