Slovakia: the Eurogroup’s enfant terrible. OSW Commentary No. 63, 2011-10-14

When Slovakia’s parliament rejected the European Financial Stability Facility (EFSF) reform on 11 October it undermined Slovakia’s reputation as a credible partner within the EU. Moreover, Prime Minister Iveta Radicova combined the vote on the strengthening of the EFSF – a key anti-crisis mechanism in the Eurozone – with a vote of confidence for her cabinet. This eventually led to the collapse of the government. Before Slovakia’s decision, the strengthening of the EFSF had been endorsed by the national parliaments of all the eurozone countries. Slovakia, which had opted to be the last one to carry out the ratification procedure, adopted the EFSF reform only in a re-vote on 13 October, due to the support of the opposition left-wing party. However, problems with ratification have cast a shadow over the achievements of Slovakia which as one of the freshest members of the eurozone had been actively seeking to influence the creation of EU mechanisms for dealing with the debt crisis. For the past eighteen months the Slovak government, formed by conservative and liberal parties, has consistently called for the controlled bankruptcy of Greece, a tightening of the rules of the Stability and Growth Pact, and for the private sector’s participation in financing the rescue packages for indebted states. It was in part down to Slovakia that these proposals, previously regarded as extreme, were introduced into the mainstream EU debate. The constructive position presented by Slovakia’s diplomacy in recent months has brought Bratislava tangible results, such as the reduction of its contribution to the permanent anti-crisis fund, the European Stabilisation Mechanism (ESM). Thus Slovakia, which adopted the single currency on 1 January 2009, has become an informal spokesman for the new, poorer members of the eurozone

Prime Minister Fico’s Russian card. OSW COMMENTARY NUMBER NUMBER 175/01.07.2015

Since the beginning of the Ukrainian-Russian conflict, the position of Slovakia’s left-wing government towards Russia has been ambiguous. Bratislava has accepted the EU sanctions targeting Russia and the plan for strengthening NATO’s eastern flank. At the same time, however, Prime Minister Robert Fico’s government has maintained close political relations with the Kremlin. It has called for the intensification of Slovak-Russian economic relations and has repeatedly criticised the sanctions, speaking in tandem with Russian propaganda in so doing. Slovakia’s Prime Minister is hoping that by playing the role of one of the leaders in the EU and NATO who are most willing to cooperate with Russia, he will gain economic benefits and win votes in next spring’s upcoming parliamentary elections. Despite numerous pro-Russian gestures, Slovakia has been limiting the number of areas in which Moscow could exert pressure on Bratislava. As it strives to become independent of Russia, Slovakia has ensured possible alternative fuel supplies for itself. Moreover, it has been gradually replacing Russian-made military equipment with equipment made in the West. The Slovak government does intend to develop the country’s cooperation with Russia, including in strategic areas involving supplies and transit of oil and gas, as well as supplies of nuclear fuel. Nevertheless, it has been making efforts to gain easy access to an alternative source of supplies in each of these areas. Beset by crises, Russia has ever fewer economic cooperation opportunities to offer Slovakia, and Slovak businesses operating on the Russian market have to take into account the growing risk of insolvency of local contractors. To a great extent, therefore, Slovak-Russian relations have been reduced to rhetorical statements confirming the desire for closer cooperation, and to visions of joint projects accompanied by an ever shorter list of feasible cooperation initiatives

Frustration and hope: Slovakia after Kuciak’s murder. OSW Point of View Number 75, July 2019

The murders of the investigative journalist Ján Kuciak and his fiancée in February 2018 became the catalyst for the civic outrage that has brought about significant changes on the Slovak political scene. This has mainly affected the long-ruling party Smer- SD and its leader Robert Fico, who resigned as prime minister under public pressure. However, the main opposition forces have benefited from the protests to only a small degree, as large sections of society perceive the opposition leaders as unreliable. New political projects have benefited from the social agitation, primarily the Progressive Slovakia party, co-founded by Zuzana Čaputová who won the presidential election in March on a wave of slogans calling for the repair of the state and the restoration of justice. The outgoing President Andrej Kiska is also forming his own political party with a centrist agenda

A neighbour discovered anew. The Czech Republic, Slovakia and Hungary’s relations with Ukraine. OSW Report August 2017

The Ukrainian-Russian war has prompted Bratislava, Prague and Budapest to take a new look at their eastern neighbourhood. Cooperation with Ukraine is gaining momentum, although relations with Russia are still the top priority for the Czech Republic, Slovakia and Hungary. Diplomatic contacts with Kyiv have been rekindled, and the Visegrad Group has intensified its political support for Ukraine within the EU. The big success in the relationship between the V4 countries and Ukraine has been their booming energy cooperation. However, the pro-Russian gestures made by some leading politicians from the Czech Republic, Slovakia and Hungary remain a challenge for relations between Bratislava, Budapest, Prague and Kyiv. Co-operation between Budapest and Kyiv is further complicated by the dispute over the Hungarian minority in Ukraine

A neighbour discovered anew. The Czech Republic, Slovakia and Hungary’s relations with Ukraine. OSW Report August 2017

The Ukrainian-Russian war has prompted Bratislava, Prague and Budapest to take a new look at their eastern neighbourhood. Cooperation with Ukraine is gaining momentum, although relations with Russia are still the top priority for the Czech Republic, Slovakia and Hungary. Diplomatic contacts with Kyiv have been rekindled, and the Visegrad Group has intensified its political support for Ukraine within the EU. The big success in the relationship between the V4 countries and Ukraine has been their booming energy cooperation. However, the pro-Russian gestures made by some leading politicians from the Czech Republic, Slovakia and Hungary remain a challenge for relations between Bratislava, Budapest, Prague and Kyiv. Co-operation between Budapest and Kyiv is further complicated by the dispute over the Hungarian minority in Ukraine

Modeling Classical Dynamics and Quantum Effects in Superconducting Circuit Systems

In recent years, superconducting circuits have come to the forefront of certain areas of physics. They have shown to be particularly useful in research related to quantum computing and information, as well as fundamental physics. This is largely because they provide a very flexible way to implement complicated quantum systems that can be relatively easily manipulated and measured. In this thesis we look at three different applications where superconducting circuits play a central role, and explore their classical and quantum dynamics and behavior. The first part consists of studying the Casimir [Proc. K. Ned. Akad. Wet (1948)] and Casimir-Polder like [Physical Review 73, 4 (1948)]effects. These effects have been discovered in 1948 and show that under certain conditions, vacuum field fluctuations can mediate forces between neutral objects. In our work, we analyze analogous behavior in a superconducting system which consists of a stripline cavity with a DC-SQUID on one of its boundaries, as well as, in a Casimir-Polder case, a charge qubit coupled to the field of the cavity. Instead of a force, in the system considered here, we show that the Casimir and Casimir-Polder like effects are mediated through a circulating current around the loop of the boundary DC-SQUID. Using detailed analysis, we examine how the values of these currents change as we vary different physical circuit parameters. We show that for the set of physical parameters that can be easily obtained experimentally, the Casimir and Casimir-Polder currents can be of the order of 10^(-8) A and 10^(-13) A respectively. In the second part, we theoretically model an experiment which was performed by Britton Plourde's group at Syracuse University, and which studied the transient dynamics of a nonlinear superconducting oscillator, based on a capacitively shunted DC-SQUID. Such DC-SQUID oscillators are used in many areas of physics and engineering, for example, as building blocks of amplifiers or qubits, qubit couplers, or as sensitive magnetic field detectors. In many of these situations, their steady state behavior is often considered, while in the experiment performed at Syracuse, of specific interest, was the response of a DC-SQUID oscillator to a short radiation that only briefly excited the system. In this thesis, we simulate this response at the experimental temperature, by numerically solving a set of classical stochastic differential equations that mimic the behavior of the circuit. This is done for different settings of the flux that is threaded through the DC-SQUID as well as different input pulse amplitudes. Furthermore, we briefly outline just how these kinds of brief excitations could be useful when applied in flux measurement protocols. We find that our simulations show good agreement with the experimentally obtained data. The final part considered in this thesis, looks at the dynamics of a qubit coupled to a measuring probe, which is modeled as a harmonic oscillator. An example superconducting circuit, that could be used to implement such a setup, consists of a flux qubit inductively coupled to a DC-SQUID. This measurement scenario has already been explored in [Phys. Rev. B 78, 5 (2008)], but there, the authors only consider very short interaction times between the DC-SQUID and the qubit. Here, in contrast, we concentrate our efforts on studying the evolution of qubit as the measurement takes place, by solving the corresponding Lindblad master equation, but over longer measurement times. This is done by calculating the measurement induced dephasing rate of the qubit, as well as, discussing its sometimes present effective relaxation, in regimes where the measurement is considered to not be quantum non-demolition (QND). Finally, we briefly explore how well a potentially complicated evolution of the qubit can be approximated as a very simple Kraus map.4 month

Surface Code Threshold Calculation and Flux Qubit Coupling

Building a quantum computer is a formidable challenge. In this thesis, we focus on two projects, which tackle very different aspects of quantum computation, and yet still share a common goal in hopefully getting us closer to implementing a quantum computer on a large scale. The first project involves a numerical error threshold calculation of a quantum error correcting code called a surface code. These are local check codes, which means that only nearest neighbour interaction is required to determine where errors occurred. This is an important advantage over other approaches, as in many physical systems, doing operations on arbitrarily spaced qubits is often very difficult. An error threshold is a measure of how well a given error correcting scheme performs. It gives the experimentalists an idea of which approaches to error correction hold greater promise. We simulate both toric and planar variations of a surface code, and numerically calculate a threshold value of approximately $6.0 \times 10^{-3}$, which is comparable to similar calculations done by others \cite{Raussendorf2006,Raussendorf2007,Wang2009}. The second project deals with coupling superconducting flux qubits together. It expands the scheme presented in \cite{Plourde2004} to a three qubit, two coupler scenario. We study L-shaped and line-shaped coupler geometries, and show how the coupling strength changes in terms of the dimensions of the couplers. We explore two cases, the first where the interaction energy between two nearest neighbour qubits is high, while the coupling to the third qubit is as negligible as possible, as well as a case where all the coupling energies are as small as possible. Although only an initial step, a similar scheme can in principle be extended further to implement a lattice required for computation on a surface code

Holes in the skies over NATO's Central European member states. OSW Commentary No. 119, 22.10.2013

Over the past few months, four Central European states have made decisions which will determine the shape of their air forces over the next decade. On 11 October, Romania signed a contract under which it will buy twelve used US F-16A/B multi-role fighter aircraft from Portugal. In August, Slovakia signed contracts with Russia’s MiG for repairs and the limited modernisation of its twelve MiG-29 fighter aircraft currently in service. The Czech Republic entered into a preliminary agreement in July with Sweden on extending the lease of fourteen JAS-39 Gripen multi-role fighter aircraft (the new Czech government will hammer out the details following the parliamentary election). Bulgaria, which has been facing financial problems and political instability, in June postponed the purchase of new (non-Soviet) combat aircraft at least until the end of this year. If Sofia decides to buy any within the next few years, these will be not more than twelve relatively old and worn-out machines (most likely F-16A/B from Portuguese or Dutch army surplus). Given the fact that Hungary in 2012 made the same decision regarding its fourteen Gripen aircraft as the Czech Republic, there are good grounds to claim that the capabilities Central European NATO member states have to take action in airspace are durably limited. The region’s saturation with combat aircraft is the lowest when compared to the entire continent (with the exception of the Baltic states). Furthermore, the machines to be used in the coming decade will be the oldest and the least advanced technologically (all of them belong to the so-called “fourth generation”, the roots of which date back to the 1970s). The problem with gaining full interoperability within NATO has not been resolved in its Central European member states. By modernising its MiG-29 aircraft, Slovakia is to say the least postponing the achievement of interoperability once again. Bulgaria will gain interoperability by buying any Western combat aircraft. However, it is very unlikely to introduce new machines into service earlier than at the end of the present decade. Since the introduction of new fifth generation multi-role combat aircraft or transitional 4+ generation machines in the region’s air forces is unrealistic, the defence of the airspace of NATO member states in Central Europe can be termed an ever more porous sky

Squeezed superradiance enables robust entanglement-enhanced metrology even with highly imperfect readout

Quantum metrology protocols using entangled states of large spin ensembles attempt to achieve measurement sensitivities surpassing the standard quantum limit (SQL), but in many cases they are severely limited by even small amounts of technical noise associated with imperfect sensor readout. Amplification strategies based on time-reversed coherent spin-squeezing dynamics have been devised to mitigate this issue, but are unfortunately very sensitive to dissipation, requiring a large single-spin cooperativity to be effective. Here, we propose a new dissipative protocol that combines amplification and squeezed fluctuations. It enables the use of entangled spin states for sensing well beyond the SQL even in the presence of significant readout noise. Further, it has a strong resilience against undesired single-spin dissipation, requiring only a large collective cooperativity to be effective.Comment: 6+9 pages, 3+3 figures; equivalent to published version; a reference to a previously unpublished manuscript has been update