A. B. Zorin

Publications (71)54.52 Total impact

• Article: Simulation of single-electron transport processes in thin granulated chromium films

  V. O. Zalunin, V. A. Krupenin, S. A. Vasenko, A. B. Zorin
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  ABSTRACT: The results of the numerical simulation of the single-electron transport in two-dimensional granulated chromium films at low temperatures are reported. A theoretical model has been developed in which the granulated film is represented as a two-dimensional matrix of conducting metallic granules (islands), which are weakly coupled with each other through slightly transparent tunnel barriers, ensuring the transport of single electrons localized on the islands. The recently measured current-voltage characteristics of submicron rectangular chromium samples have been explained by taking into account the inhomogeneities in the nanometer sizes of the islands and their effective electron temperature depending on the flowing current. A transition from the two-dimensional regime to the quasi-one-dimensional regime of the single-electron transport leading to the experimentally observed hysteresis has been revealed in the simulated system.
  JETP Letters 04/2012; 91(8):402-406. · 1.35 Impact Factor
• Article: A hybrid superconductor-normal metal electron trap as a photon detector

  S. V. Lotkhov, A. B. Zorin
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  ABSTRACT: A single-electron trap built with two Superconductor (S) - Insulator (I) - Normal (N) metal tunnel junctions and coupled to a readout SINIS-type single-electron transistor A (SET A) was studied in a photon detection regime. As a source of photon irradiation, we used an operating second SINIS-type SET B positioned in the vicinity of the trap. In the experiment, the average hold time of the trap was found to be critically dependent on the voltage across SET B. Starting in a certain voltage range, a photon-assisted electron escape was observed at a rate roughly proportional to the emission rate of the photons with energies exceeding the superconducting gap of S-electrodes in the trap. The discussed mechanism of photon emission and detection is of interest for low-temperature noise spectrometry and it can be of relevance for the ampere standard based on hybrid SINIS turnstiles.
  04/2012;
• Source

  Available from: Dmitri V. Averin

  Conference Proceeding: Radio-frequency transport of single electrons in superconductor-normal-metal tunnel junctions and the quantum metrological triangle

  A. Kemppinen, V.F. Maisi, O. Saira, S. Kafanov, S.V. Lotkhov, Yu.A. Pashkin, T. Aref, M. Meschke, M. Mottonen, O. Hahtela, J. Hassel, J. Luomahaara, E. Mykkanen, H. Koivula, D.V. Averin, H. Seppa, J.S. Tsai, A.B. Zorin, A. Manninen, J.P. Pekola
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  ABSTRACT: We are developing a single-electron turnstile based on a nanoscale superconductor-insulator-normal-metal-insulator-superconductor (SINIS) structure. The goal is to obtain the frequency to current conversion I = ef with a relative uncertainty <; 10^-8 which would be sufficient for a quantum-based standard of electric current. Finally, the quantum current standard will be compared against the quantum standards of voltage and resistance via Ohm's law in the quantum metrological triangle experiment.
  General Assembly and Scientific Symposium, 2011 XXXth URSI; 09/2011
• Source

  Available from: Antti Kemppinen

  Article: Long hold times in a two-junction electron trap

  A. Kemppinen, S. V. Lotkhov, O. -P. Saira, A. B. Zorin, J. P. Pekola, A. J. Manninen
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  ABSTRACT: The hold time $\tau$ of a single-electron trap is shown to increase significantly due to suppression of environmentally assisted tunneling events. Using two rf-tight radiation shields instead of a single one, we demonstrate increase of $\tau$ by a factor exceeding $10^3$, up to about 10 hours, for a trap with only two superconductor (S) -- normal-metal (N) tunnel junctions and an on-chip resistor $R$ (R-SNS structure). In the normal state, the improved shielding made it possible to observe $\tau\sim$ 100 s, which is in reasonable agreement with the quantum-leakage-limited level expected for the two-electron cotunneling process.
  08/2011;
• Source

  Available from: ArXiv

  Article: Implementation of superconductor-ferromagnet-superconductor pi-shifters in superconducting digital and quantum circuits

  A. K. Feofanov, V. A. Oboznov, V. V. Bol'ginov, J. Lisenfeld, S. Poletto, V. V. Ryazanov, A. N. Rossolenko, M. Khabipov, D. Balashov, A. B. Zorin, P.N. Dmitriev, V.P. Koshelets, A. V. Ustinov
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  ABSTRACT: The difference between the phases of superconducting order parameter plays in superconducting circuits the role similar to that played by the electrostatic potential difference required to drive a current in conventional circuits. This fundamental property can be altered by inserting in a superconducting circuit a particular type of weak link, the so-called Josephson $\pi$-junction having inverted current-phase relation and enabling a shift of the phase by $\pi$. We demonstrate the operation of three superconducting circuits -- two of them are classical and one quantum -- which all utilize such $\pi$-phase shifters realized using superconductor-ferromagnet-superconductor sandwich technology. The classical circuits are based on single-flux-quantum cells, which are shown to be scalable and compatible with conventional niobium-based superconducting electronics. The quantum circuit is a $\pi$-phase biased qubit, for which we observe coherent Rabi oscillations and compare the measured coherence time with that of conventional superconducting phase qubits. Comment: 14 pages, 4 figures
  05/2010;
• Source

  Available from: itp.ac.ru

  Article: A single flux quantum circuit with a ferromagnet-based Josephson π-junction

  M I Khabipov, D V Balashov, F Maibaum, A B Zorin, V A Oboznov, V V Bolginov, A N Rossolenko, V V Ryazanov
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  ABSTRACT: We report on the functionality of a Nb-based superconducting single flux quantum (SFQ) toggle flip-flop (TFF) circuit, comprising a complementary superconductor–ferromagnet–superconductor (SFS) Josephson π-junction. The SFS junction was used as a phase shifting element inserted in the storage loop of the TFF. The fabricated circuits demonstrated correct functionality with the operation parameter ranges of ± 20%. The application of SFS π-junctions makes the SFQ circuits very compact, may substantially improve their stability, and may also be suitable for integration with Josephson quantum circuits (qubits).
  Superconductor Science and Technology 03/2010; 23(4):045032. · 2.66 Impact Factor
• Source

  Available from: Fabio Chiarello

  Article: Superconducting phase qubit based on the Josephson oscillator with strong anharmonicity

  A. B. Zorin, F. Chiarello
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  ABSTRACT: We propose a superconducting phase qubit on the basis of the radio-frequency SQUID with the screening parameter value $\beta_L = (2\pi/\Phi_0)LI_c \approx 1$, biased by a half flux quantum $\Phi_e=\Phi_0/2$. Significant anharmonicity ($> 30%$) can be achieved in this system due to the interplay of the cosine Josephson potential and the parabolic magnetic-energy potential that ultimately leads to the quartic polynomial shape of the well. The two lowest eigenstates in this global minimum perfectly suit for the qubit which is insensitive to the charge variable, biased in the optimal point and allows an efficient dispersive readout. Moreover, the transition frequency in this qubit can be tuned within an appreciable range allowing variable qubit-qubit coupling. Comment: 5 pages incl. 5 figures
  08/2009;
• Conference Proceeding: Shunt-protected single-electron tunneling circuits fabricated on a quartz wafer

  S.V. Lotkhov, B. Camarota, H. Scherer, T. Weimann, P. Hinze, A.B. Zorin
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  ABSTRACT: We address fabrication challenges for the single-electron tunneling (SET) devices, based on ultrasmall junctions Al/AlO_x/Al. Nanoscale SET components are known to be very fragile in respect to electrostatic breakdown, which turns out to be a critical problem for devices, fabricated on insulating substrates. For the breakdown prevention, we successfully realized on-chip silicon shunts, whose conductivity advantageously vanished at low temperatures, making possible undisturbed SET operation at T ~ 100 mK.
  Nanotechnology Materials and Devices Conference, 2009. NMDC '09. IEEE; 07/2009
• Article: Quantum dynamics of superconducting nano-circuits: phase qubit, charge qubit and rhombi chains

  O. Buisson, W. Guichard, F. W. J. Hekking, L. Lévy, B. Pannetier, R. Dolata, A. B. Zorin, N. Didier, A. Fay, E. Hoskinson, F. Lecocq, Z. H. Peng, I. M. Pop
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  ABSTRACT: We have studied different quantum dynamics of superconducting nano-circuits with Josephson junctions. A dc SQUID, when it is strongly decoupled from the environment, demonstrates two-level and multilevel dynamics. We have realized a two qubits coupled circuit based on a dc SQUID in parallel with an asymmetric Cooper pair transistor (ACPT). The ACPT behaves as a charge qubit. Its asymmetry produces a strong tunable coupling with the dc SQUID which is used to realize entangled states between the two qubits and new read-out of the charge qubit based on adiabatic quantum transfer. We have measured the current–phase relations of different rhombi chains in the presence or absence of quantum fluctuations which confirm theoretical predictions.
  Quantum Information Processing 05/2009; 8(2):155-182. · 2.00 Impact Factor
• Source

  Available from: Antti Kemppinen

  Article: Pumping properties of the hybrid single-electron transistor in dissipative environment

  S. V. Lotkhov, A. Kemppinen, S. Kafanov, J. P. Pekola, A. B. Zorin
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  ABSTRACT: Pumping characteristics were studied of the hybrid normal-metal/superconductor single-electron transistor embedded in a high-ohmic environment. Two 3 micrometer-long microstrip resistors of CrOx with a sum resistance R=80kOhm were placed adjacent to this hybrid device. Substantial improvement of pumping and reduction of the subgap leakage were observed in the low-MHz range. At higher frequencies 0.1-1GHz, a slowdown of tunneling due to the enhanced damping and electron heating negatively affected the pumping, as compared to the reference bare devices. Comment: 3 pages 4 figures
  05/2009;
• Article: Quantum dynamics in a camelback potential of a dc SQUID.

  E Hoskinson, F Lecocq, N Didier, A Fay, F W J Hekking, W Guichard, O Buisson, R Dolata, B Mackrodt, A B Zorin
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  ABSTRACT: We investigate a quadratic-quartic anharmonic oscillator formed by a potential well between two potential barriers. We realize this novel potential with a dc SQUID at near-zero current bias and flux bias near half a flux quantum. Escape out of the central well can occur via tunneling through either of the two barriers. We find good agreement with a generalized double-path macroscopic quantum tunneling theory. We also demonstrate an "optimal line" in current and flux bias along which the oscillator, which can be operated as a phase qubit, is insensitive to decoherence due to low-frequency current fluctuations.
  Physical Review Letters 04/2009; 102(9):097004. · 7.37 Impact Factor
• Source

  Available from: ArXiv

  Article: Modeling of quasiparticle-induced excitations of a Josephson charge-phase qubit

  J. Könemann, H. Zangerle, B. Egeling, R. Harke, B. Mackrodt, R. Dolata, A. B. Zorin
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  ABSTRACT: We have analyzed quasiparticle transitions in an Al charge-phase qubit inducing a dynamic change of the qubit states. The time-averaged mixed state is related to the strong coupling of the qubit to an ensemble of non-equilibrium quasiparticles in the leads. Such quasiparticles tunnel stochastically on and off the island and can excite the qubit. Continuous monitoring of the qubit impedance at a frequency of 80 MHz shows the admixture of the excited state. We present a numerical description of these cyclic transitions and compare it with our experimental data.
  09/2008;
• Article: Characterization and metrological investigation of an R-pump with driving frequencies up to 100 MHz

  B Steck, A Gonzalez-Cano, N Feltin, L Devoille, F Piquemal, S Lotkhov, A B Zorin
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  ABSTRACT: The stability of an electron pump composed of three junctions and on-chip chromium resistors at the ends is investigated as a function of applied frequencies on the gate electrodes. For the first time current steps have been obtained with frequencies fSET as high as 100 MHz. Moreover in the complete studied frequency range we show that the nature (white) and the level of the noise are independent of pumping speed within the noise floor. By generating a single-electron current close to 16.02 pA and measuring over 7 h, a relative type A uncertainty has been found of 3.9 parts in 106. Although the experimental set-up described in this paper does not allow one to measure accurately an absolute value of the current, an alternative set-up including an external current source is proposed for investigating the eventual deviation of the current from the quantization level, e fSET. As a matter of fact this set-up proves to be similar to the quantum metrological triangle experiment (QMT). We have demonstrated that the electron R-pump is a plausible candidate for closing the QMT experiment with a type A uncertainty level of 10−6.
  Metrologia 08/2008; 45(4):482. · 1.75 Impact Factor
• Source

  Available from: Pasquale Carelli

  Article: An Optimal Tunable Josephson Element for Quantum Computing

  F. Chiarello, M. G. Castellano, G. Torrioli, S. Poletto, C. Cosmelli, P. Carelli, D. V. Balashov, M. I. Khabipov, A. B. Zorin
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  ABSTRACT: We introduce a three-junction SQUID that can be effectively used as an optimal tunable element in Josephson quantum computing applications. This device can replace the simple dc SQUID generally used as tunable element in this kind of applications, with a series of advantages for the coherence time and for the tolerance to small errors. We study the device both theoretically and experimentally at 4.2 K, obtaining a good agreement between the results.
  06/2008;
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  Available from: ArXiv

  Article: Single flux quantum circuits with damping based on dissipative transmission lines

  E. M. Tolkacheva, D. V. Balashov, M. I. Khabipov, A. B. Zorin
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  ABSTRACT: We propose and demonstrate the functioning of a special Rapid Single Flux Quantum (RSFQ) circuit with frequency-dependent damping. This damping is achieved by shunting individual Josephson junctions by pieces of open-ended RC transmission lines. Our circuit includes a toggle flip-flop cell, Josephson transmission lines transferring single flux quantum pulses to and from this cell, as well as DC/SFQ and SFQ/DC converters. Due to the desired frequency-dispersion in the RC line shunts which ensures sufficiently low noise at low frequencies, such circuits are well-suited for integrating with the flux/phase Josephson qubit and enable its efficient control.
  05/2008;
• Article: Low-noise RSFQ circuits for a Josephson Qubit control

  M Khabipov, D Balashov, E Tolkacheva, A B Zorin
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  ABSTRACT: We address the problem of reducing the noise of an RSFQ circuit, which may significantly decohere a Josephson qubit in the case of integration of these circuits. The main sources of such noise in traditional RSFQ circuits are low-ohmic shunting resistors ensuring sufficiently high damping. We developed the toggle flip-flop (TFF) cells with weakly-damped individual junctions due to high-ohmic shunts. The dominant part of necessary damping in this circuit was realized by applying an additional, so-called 'perpendicular', low-ohmic resistor connecting the centre of the storing TFF inductance to ground. The TFF circuits with junctions shunted by 50 Ω resistors and perpendicular resistor of 1.5 Ω, ensuring suppression of noise by more than one order, have been fabricated and demonstrated an operation range of ±20%. In order to make the circuit compact and, therefore, less sensitive to external noise, the passive frozen-flux-based phase shifting elements, replacing large quantizing inductances, were also included. The circuits were fabricated using PTB Nb trilayer process with critical current density jc = 100 A/cm2.
  Journal of Physics Conference Series 03/2008; 97(1):012041.
• Article: Implementation of superconductive passive phase shifters in high-speed integrated RSFQ digital circuits

  B Dimov, D Balashov, M Khabipov, Th Ortlepp, F-Im Buchholz, A B Zorin, J Niemeyer, F H Uhlmann
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  ABSTRACT: The reduction of the critical current density in rapid single-flux quantum (RSFQ) circuits enables new application fields, like quantum computing and photonic detector readout. The low current density fabrication process creates new design challenges, such as lower stability against thermal fluctuations, violation of the lumped elements condition for microstrip inductances and increased sensitivity to the technological spread. To overcome these issues, we suggest a passive phase shifter as a promising alternative technique for superconductive phase dropping in the RSFQ electronics. Here, we study experimentally their applicability in high-speed RSFQ digital circuits. Conclusions are drawn about the impact of the passive phase shifters on the complexity, the speed and the bit error rate of the investigated RSFQ circuits. We demonstrate the successful operation of different circuits with implemented passive phase shifters at low and high speeds.
  Superconductor Science and Technology 02/2008; 21(4):045007. · 2.66 Impact Factor
• Article: Superconductive passive phase shifter for integrated RSFQ digital circuits

  B Dimov, D Balashov, M Khabipov, Th Ortlepp, F-Im Buchholz, A B Zorin, J Niemeyer, F H Uhlmann
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  ABSTRACT: A vital precondition for the realization of rapid single-flux quantum (RSFQ) digital circuits with reduced critical currents of the Josephson junctions is the implementation of an efficient technique for superconductive phase dropping. In this paper, we present a novel phase shifting element consisting of a miniature superconductive ring located over a ground plane hole. Contrary to the solutions reported up to now, this topology can be simply integrated within complex digital RSFQ circuits realized with conventional fabrication technology.
  Superconductor Science and Technology 10/2007; 20(11):S332. · 2.66 Impact Factor
• Article: Passive Phase Shifter for Superconducting Josephson Circuits

  D. Balashov, B. Dimov, M. Khabipov, T. Ortlepp, D. Hagedorn, A.B. Zorin, F.-I. Buchholz, F.H. Uhlmann, J. Niemeyer
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  ABSTRACT: Quantized values of magnetic flux trapped in a superconducting loop enable a new type of passive phase shifting elements. These elements can be incorporated into digital Josephson circuits making their design compact. We have proven the functionality of such phase shifters fabricated in conventional Nb/Al trilayer technology. We report on the successful low speed operation of a rapid single flux quantum toggle flip-flop circuit with the integrated passive pi-phase shifting element.
  IEEE Transactions on Appiled Superconductivity 07/2007; · 1.04 Impact Factor
• Article: Cooper Pair Transport in a Resistor-Biased Josephson Junction Array

  S.V. Lotkhov, V.A. Krupenin, A.B. Zorin
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  ABSTRACT: The dc transport properties of long arrays of small Al Josephson junctions, biased through on-chip Cr resistors, are studied. The IV characteristics show a large Coulomb threshold for current as well as negative-slope regions indicating the regime of autonomous Bloch oscillations up to rather high frequencies of f = I/2e ~ 1 GHz, comparable to those reported by other groups for single junctions. On the other hand, a small depth of the back-bending implies a low duty cycle and a broad spectrum of the oscillations, which we attribute to the insufficiently high impedance of the bias resistors. A self-sustained switching process at a small bias current is used to study the statistics of the switching voltages and to determine the effective Bloch capacitance which was found to considerably exceed the geometric junction capacitance
  IEEE Transactions on Instrumentation and Measurement 05/2007; · 1.21 Impact Factor