Rabi spectroscopy of a strongly driven qubit-fluctuator system (2009)
Lisenfeld, Juergen, Mueller, Clemens, Cole, Jared H., Lukashenko, Alexander, Shnirman, Alexander, Ustinov, Alexey V.
Superconducting qubits often show signatures of coherent coupling to microscopic two-level fluctuators (TLFs), which manifest themselves as avoided level crossings in spectroscopic data. In this work...
Few-Qubit lasing in circuit QED (2009)
André, Stephan, Brosco, Valentina, Marthaler, Michael, Shnirman, Alexander, Schön, Gerd
Motivated by recent experiments, which demonstrated lasing and cooling of the electromagnetic modes in a resonator coupled to a superconducting qubit, we describe the specific mechanisms creating the...
Relaxation of Josephson qubits due to strong coupling to two-level systems (2009)
Müller, Clemens, Shnirman, Alexander, Makhlin, Yuriy
We investigate the energy relaxation (T1) process of a qubit coupled to a bath of dissipative two-level fluctuators (TLF). We consider the fluctuators strongly coupled to the qubit both in the limit...
Pletyukhov, Mikhail, Shnirman, Alexander
We consider the magnetic response of a two-dimensional electron gas (2DEG) with both Rashba and Dresselhaus spin-orbit coupling to a microwave excitation. We generalize the results of [A. Shnirman...
Phase diffusion and locking in single-qubit lasers (2008)
André, Stephan, Brosco, Valentina, Shnirman, Alexander, Schön, Gerd
Motivated by recent experiments, which demonstrated lasing and cooling of the electromagnetic field in an electrical resonator coupled to a superconducting qubit, we study the spectral properties of...
Hauss, Julian, Fedorov, Arkady, André, Stephan, Brosco, Valentina, Hutter, Carsten, Kothari, Robin, ...
Superconducting qubits coupled to electric or nanomechanical resonators display effects previously studied in quantum electrodynamics (QED) and extensions thereof. Here we study a driven qubit...
Geometric effects of noise on Cooper pair pumping (2008)
Brosco, Valentina, Shnirman, Alexander, Fazio, Rosario
Several works investigated the connection between Cooper pair pumping and the geometric and topological properties of the pumping cycle in the parameters space. Recently the predicted connection...
Photon-Number Squeezing in Circuit Quantum Electrodynamics (2008)
Marthaler, M., Schön, Gerd, Shnirman, Alexander
A superconducting single-electron transistor (SSET) coupled to an anharmonic oscillator, e.g., a Josephson junction-L-C circuit, can drive the latter to a nonequilibrium photon number state. By...
QUANTUM COMPUTING AND JOSEPHSON JUNCTION CIRCUITS (2007)
Abstract: Among possible realizations of quantum computing systems nano-electronic circuits appear very promising as they can be easily scaled up to large numbers of qubits and integrated in...
Nano-Electronic Circuits as Quantum Bits (2007)
Yuriy Makhlin, Gerd Schön, Alexander Shnirman
Quantum information processing systems can be used in a variety of applications. Among proposed realizations of quantum bits nano-electronic circuits appear most promising for integration in...
Josephson Junction based Quantum Computing (2007)
Yuriy Makhlin, Gerd Schön, Alexander Shnirman
. Among the physical realizations of the elements required for quantum computation nano-scale electronic devices [15,2,12,10] are very promising. They can be easily integrated into electronic...
Geometric phases in semiconductor spin qubits: Manipulations and decoherence (2007)
San-Jose, Pablo, Scharfenberger, Burkhard, Schön, Gerd, Shnirman, Alexander, Zarand, Gergely
We describe the effect of geometric phases induced by either classical or quantum electric fields acting on single electron spins in quantum dots in the presence of spin-orbit coupling. On one hand,...
Towards a dephasing diode: asymmetric and geometric dephasing (2007)
Whitney, Robert S., Shnirman, Alexander, Gefen, Yuval
We study the effect of a noisy environment on spin and charge transport in ballistic quantum wires with spin-orbit coupling (Rashba coupling). We find that the wire then acts as a ``dephasing...
Geometrical Spin Dephasing in Quantum Dots (2007)
San-Jose, Pablo, Zarand, Gergely, Shnirman, Alexander, Schön, Gerd
Spin dephasing due to a random Berry phase (2007)
San-Jose, Pablo, Schön, Gerd, Shnirman, Alexander, Zarand, Gergely
We investigate relaxation and dephasing of an electron spin confined in a semiconductor quantum dot and subject to spin-orbit coupling. Even in vanishing magnetic field, B = 0, slow noise coupling to...
Stability of longitudinal coupling for Josephson charge qubits (2007)
Hutter, Carsten, Makhlin, Yuriy, Shnirman, Alexander, Schön, Gerd
For inductively coupled superconducting quantum bits, we determine the conditions when the coupling commutes with the single-qubit terms. We show that in certain parameter regimes such longitudinal...
Single-qubit lasing and cooling at the Rabi frequency (2007)
Hauss, Julian, Fedorov, Arkady, Hutter, Carsten, Shnirman, Alexander, Schön, Gerd
For a superconducting qubit driven to perform Rabi oscillations and coupled to a slow electromagnetic or nano-mechanical oscillator we describe previously unexplored quantum optics effects. When the...
Reading-out the state of a flux qubit by Josephson transmission line solitons (2006)
Fedorov, Arkady, Shnirman, Alexander, Schön, Gerd, Kidiyarova-Shevchenko, Anna
We describe the read-out process of the state of a Josephson flux qubit via solitons in Josephson transmission lines (JTL) as they are in use in the standard rapid single flux quantum (RSFQ)...
Spin-density induced by electromagnetic wave in two-dimensional electron gas (2006)
Shnirman, Alexander, Martin, Ivar
We consider the magnetic response of a two-dimensional electron gas (2DEG) with a spin-orbit interaction to a long-wave-length electromagnetic excitation. We observe that the transverse electric...
Geometrical spin dephasing in quantum dots (2006)
San-Jose, Pablo, Zarand, Gergely, Shnirman, Alexander, Schön, Gerd
We study spin-orbit mediated relaxation and dephasing of electron spins in quantum dots. We show that higher order contributions provide a relaxation mechanism that dominates for low magnetic fields...
Tunable coupling of qubits: nonadiabatic corrections (2006)
Hutter, Carsten, Shnirman, Alexander, Makhlin, Yuriy, Schön, Gerd
We analyze the coupling of qubits mediated by a tunable and fast element beyond the adiabatic approximation. The nonadiabatic corrections are important and even dominant in parts of the relevant...
Decoherence from ensembles of two-level fluctuators (2005)
Schriefl, Josef, Makhlin, Yuriy, Shnirman, Alexander, Schön, Gerd
1/f noise, the major source of dephasing in Josephson qubits, may be produced by an ensemble of two-level systems. Depending on the statistical properties of their distribution, the noise...
Low- and high-frequency noise from coherent two-level systems (2004)
Shnirman, Alexander, Schön, Gerd, Martin, Ivar, Makhlin, Yuriy
Recent experiments indicate a connection between the low- and high-frequency noise affecting superconducting quantum systems. We explore the possibilities that both noises can be produced by one...
Spin and Spin-Wave Dynamics in Josephson Junctions (2004)
Nussinov, Zohar, Shnirman, Alexander, Arovas, Daniel P., Balatsky, Alexander V., Zhu, Jian-Xin
We extend the Keldysh formulation to quantum spin systems and derive exact equations of motion. This allows us to explore the dynamics of single spins and of ferromagnets when these are inserted...
Geometric nature of the environment-induced Berry phase and geometric dephasing (2004)
Whitney, Robert S., Makhlin, Yuriy, Shnirman, Alexander, Gefen, Yuval
We investigate the geometric phase or Berry phase (BP) acquired by a spin-half which is both subject to a slowly varying magnetic field and weakly-coupled to a dissipative environment (either quantum...
Cavity QED in superconducting circuits: susceptibility at elevated temperatures (2004)
Rau, Ileana, Johansson, Göran, Shnirman, Alexander
We study the properties of superconducting electrical circuits, realizing cavity QED. In particular we explore the limit of strong coupling, low dissipation, and elevated temperatures relevant for...
Berry phase with environment: classical versus quantum (2004)
Whitney, Robert S., Makhlin, Yuriy, Shnirman, Alexander, Gefen, Yuval
We discuss the concept of the Berry phase in a dissipative system. We show that one can identify a Berry phase in a weakly-dissipative system and find the respective correction to this quantity,...
Dephasing of qubits by transverse low-frequency noise (2003)
Makhlin, Yuriy, Shnirman, Alexander
We analyze the dissipative dynamics of a two-level quantum system subject to low-frequency, e.g. 1/f noise, motivated by recent experiments with superconducting quantum circuits. We show that the...
Quantum Zeno effect in the Cooper-pair transport through a double-island Josephson system (2003)
Shnirman, Alexander, Makhlin, Yuriy
Motivated by recent experiments, we analyze transport of Cooper pairs through a double-island Josephson qubit. At low bias in a certain range of gate voltages coherent superpositions of charge states...
Ground state cooling of mechanical resonators (2003)
Martin, Ivar, Shnirman, Alexander, Tian, Lin, Zoller, Peter
We propose an application of a single Cooper pair box (Josephson qubit) for active cooling of nanomechanical resonators. Latest experiments with Josephson qubits demonstrated that long coherence time...
Dissipation in Josephson qubits (2003)
Makhlin, Yuriy, Schön, Gerd, Shnirman, Alexander
We discuss the dissipative dynamics of superconducting qubits in the applicability range of the Bloch equations and beyond.
Dephasing of solid-state qubits at optimal points (2003)
Makhlin, Yuriy, Shnirman, Alexander
Motivated by recent experiments with Josephson-junction circuits, we analyze the influence of various noise sources on the dynamics of two-level systems at optimal operation points where the linear...
Novel Spin Dynamics in a Josephson Junction (2003)
Zhu, Jian-Xin, Nussinov, Zohar, Shnirman, Alexander, Balatsky, Alexander V.
We address the dynamics of a single spin embedded in the tunneling barrier between two superconductors. As a consequence of pair correlations in the superconducting state, the spin displays a rich...
Spin-spin correlators in Majorana representation (2003)
Shnirman, Alexander, Makhlin, Yuriy
In the Majorana representation of a spin 1/2 we find an identity which relates spin-spin correlators to one-particle fermionic correlators. This should be contrasted with the straightforward approach...
Dephasing and Renormalization in Quantum Two-Level Systems (2002)
Shnirman, Alexander, Schön, Gerd
Motivated by fundamental questions about the loss of phase coherence at low temperature we consider relaxation, dephasing and renormalization effects in quantum two-level systems which are coupled to...
Noise and decoherence in quantum two-level systems (2002)
Shnirman, Alexander, Makhlin, Yuriy, Schön, Gerd
Motivated by recent experiments with Josephson-junction circuits we reconsider decoherence effects in quantum two-level systems (TLS). On one hand, the experiments demonstrate the importance of 1/f...
Quantum state engineering with Josephson-junction devices (2000)
Makhlin, Yuriy, Schoen, Gerd, Shnirman, Alexander
We review recent theoretical and experimental progress in quantum state engineering with Josephson junction devices. The concepts of quantum computing have stimulated an increased activity in the...
Statistics and noise in a quantum measurement process (2000)
Makhlin, Yuriy, Schoen, Gerd, Shnirman, Alexander
The quantum measurement process by a single-electron transistor or a quantum point contact coupled to a quantum bit is studied. We find a unified description of the statistics of the monitored...
Nano-electronic Realizations of Quantum Bits (1999)
Makhlin, Yuriy, Schoen, Gerd, Shnirman, Alexander
Quantum computers could perform certain tasks which no classical computer can perform in acceptable times. Josephson junction circuits can serve as building blocks of quantum computers. We discuss...
Adagideli, Inanc, Goldbart, Paul M., Shnirman, Alexander, Yazdani, Ali
Low-energy quasiparticle states, arising from scattering by single-particle potentials in d-wave superconductors, are addressed. Via a natural extension of the Andreev approximation, the idea that...
Shnirman, Alexander, Adagideli, Inanc, Goldbart, Paul M., Yazdani, Ali
We examine the role of order-parameter suppression in the development of low-energy peaks (i.e., resonances) in the tunneling density of states near a non-magnetic impurity in a d-wave...
Nano-Electronic Realizations Of Quantum Bits (1999)
Yuriy Makhlin, Gerd Schön, Alexander Shnirman
INTRODUCTION Quantum computers, if available, could perform certain operations in a massive parallel way, which would lead to an exponential speed-up as compared to the performance of classical...
Josephson-Junction Qubits and the Readout Process by Single-Electron Transistors (1998)
Makhlin, Yuriy, Schoen, Gerd, Shnirman, Alexander
Several physical realizations of quantum bits have been proposed. Of those, nano-electronic devices appear most suitable for large-scale integration and potential applications. We suggest to use...
Josephson-Junction Qubits with Controlled Couplings (1998)
Makhlin, Yuriy, Schoen, Gerd, Shnirman, Alexander
Low-capacitance Josephson junctions, where Cooper pairs tunnel coherently while Coulomb blockade effects allow the control of the total charge, provide physical realizations of quantum bits (qubits),...
Quantum Measurements Performed with a Single-Electron Transistor (1998)
Shnirman, Alexander, Schoen, Gerd
Low-capacitance Josephson junction systems as well as coupled quantum dots, in a parameter range where single charges can be controlled, provide physical realizations of quantum bits, discussed in...
Quantum Manipulations of Small Josephson Junctions (1997)
Shnirman, Alexander, Schoen, Gerd, Hermon, Ziv
Low-capacitance Josephson junction arrays in the parameter range where single charges can be controlled are suggested as possible physical realizations of the elements which have been considered in...
Alexander Shnirman, Yuriy Makhlin, Gerd Schön
Introduction The investigation of nano-scale electronic devices, such as low-capacitance tunnel junctions or quantum dot systems, has always been motivated by the perspective of future applications....
Ben-Jacob, Eshel, Guinea, Francisco, Hermon, Ziv, Shnirman, Alexander
We propose the existence and study the solitonic excitations in two kinds of samples in the fractional quantum Hall regime. One is a strip modulated by a one-dimensional array of gates. The other is...