相关论文: Decoherence processes in a current biased dc SQUID
In this paper we study the low temperature kinetics of the electrons in the system composed of a quantum dot connected to two leads by solving the equation of motion. The decoherence and the relaxation of the system caused by the gate…
We developed a scanning DC SQUID microscope with novel readout electronics capable of wideband sensing RF magnetic fields from 50 to 200 MHz and simultaneously providing closed-loop response at kHz frequencies. To overcome the 20 MHz…
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 coupling to low-frequency fluctuations is…
We present a quantum open-system approach to analyze the nonunitary dynamics of a superconducting qubit when it evolves under the influence of external noise. We consider the presence of longitudinal and transverse environmental…
We investigate the effects of noise-induced coherence on average current and current fluctuations in a simple model of quantum absorption refrigerator with degenerate energy levels. We describe and explain the differences and similarities…
We explore a strategy for protecting the evolution of a qubit against the effects of environmental noise based on the application of controlled time-dependent perturbations. In the case of a purely decohering coupling, an explicit sequence…
Dielectric constant and absorption measurements on boron doped silicon samples show that transitions between the acceptor energy levels can be induced by an applied resonant ac electric field and the Stark tuning of level spacing with an…
We study decoherence of the Josephson charge qubit by measuring energy relaxation and dephasing with help of the single-shot readout. We found that the dominant energy relaxation process is a spontaneous emission induced by quantum noise…
A theory for the voltage-current characteristic in high TC DC SQUIDs, which accounts for a second harmonic in the junction current-phase relation, is developed. The comparison with experiment is performed. It is shown that if the second…
A double quantum dot device is a tunable two-level system for electronic energy states. A dc electron current directly measures the rates for elastic and inelastic transitions between the two levels. For inelastic transitions energy is…
Noise in entangled quantum systems is difficult to characterize due to many-body effects involving multiple degrees of freedom. This noise poses a challenge to quantum computing, where two-qubit gate performance is critical. Here, we…
We report measurements of the low frequency current fluctuations of a tunnel junction placed at very low temperature biased by a time-dependent voltage $V(t)=V(1+\cos 2\pi\nu t)$. We observe that the excess noise generated by the ac…
The interaction between a qubit and its environment provides a channel for energy relaxation which has an energy-dependent timescale governed by the specific coupling mechanism. We measure the rate of inelastic decay in a Si MOS double…
Characterizing and understanding noise affecting quantum states has immense benefits in spectroscopy as well as in realizing quantum devices. Transverse relaxation times under a set of dynamical decoupling (DD) sequences with varying…
The quantum dynamics of a compound sample consisting from a semiconductor double quantum dot (DQD) system non-linearly coupled with a leaking single-mode micro-resonator is theoretically investigated. The focus is on the resonance condition…
A new DC-SQUID is proposed that exploits the properties of the grain boundary junctions in high T_c superconductors. The orientations of the grain boundaries are chosen in such a way to establish a pi/2 (rather than 0 or pi) phase…
The operational dc-SQUID based on intrinsic Josephson junctions in Bi$_2$Sr$_2$CaCu2O$_{8+\delta}$ high-$T_c$ superconductor is fabricated and studied. The novel in-plane loop layout and the developed in-situ endpoint detection method…
The qubit (or a system of two quantum dots) has become a standard paradigm for studying quantum information processes. Our focus is Decoherence due to interaction of the qubit with its environment, leading to noise. We consider quantum…
We present a theoretical analysis of the quantum dynamics of a superconducting circuit based on a highly asymmetric Cooper pair transistor (ACPT) in parallel to a dc-SQUID. Starting from the full Hamiltonian we show that the circuit can be…
We compute the decoherence caused by $1/f$ fluctuations at low frequency $f$ in the critical current $I_0$ of Josephson junctions incorporated into flux, phase, charge and hybrid flux-charge superconducting quantum bits (qubits). The…