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Quantum annealing is a method to solve optimization problems that leverages quantum tunneling in a coupled qubit system. We present a detailed study of the coherence of a tunable capacitively-shunted flux qubit, designed for coherent…

The fluxonium qubit has arisen as one of the most promising candidate devices for implementing quantum information in superconducting devices, since it is both insensitive to charge noise (like flux qubits) and insensitive to flux noise…

Mesoscale and Nanoscale Physics · Physics 2015-07-20 Samuele Spilla , Fabian Hassler , Anna Napoli , Janine Splettstoesser

Charge excitations in a two dimensional electron gas, under a quantizing magnetic field and in the fractional quantum Hall effect regime, flow in one dimensional-like strips along the edges of the sample. These excitations (quasiparticles)…

Mesoscale and Nanoscale Physics · Physics 2009-12-25 Moty Heiblum

A qubit (containing two quantum states, 1 and 2), is coupled to a control register (state 3), which is subject to telegraph noise. We study the time evolution of the density matrix $\rho$ of an electron which starts in some coherent state…

Mesoscale and Nanoscale Physics · Physics 2009-09-01 Amnon Aharony , Ora Entin-Wohlman , Sushanta Dattagupta

In order to gain a better understanding of the origin of decoherence in superconducting flux qubits, we have measured the magnetic field dependence of the characteristic energy relaxation time ($T_1$) and echo phase relaxation time…

Superconductivity · Physics 2009-11-11 K. Kakuyanagi , T. Meno , S. Saito , H. Nakano , K. Semba , H. Takayanagi , F. Deppe , A. Shnirman

We implement dynamical decoupling techniques to mitigate noise and enhance the lifetime of an entangled state that is formed in a superconducting flux qubit coupled to a microscopic two-level system. By rapidly changing the qubit's…

In a 'controlled dephasing' experiment [1-3], an interferometer loses its coherence due to entanglement with a controlled quantum system ('which path' detector). In experiments that were conducted thus far in mesoscopic systems only partial…

Mesoscale and Nanoscale Physics · Physics 2015-06-25 I. Neder , F. Marquardt , M. Heiblum , D. Mahalu , V. Umansky

In this study, we investigate the decoherence of a spatially superposed electrically neutral spin-$\frac12$ particle in the presence of a relativistic quantum electromagnetic field in Minkowski spacetime. We demonstrate that decoherence due…

Quantum Physics · Physics 2024-10-30 Kensuke Gallock-Yoshimura , Yuuki Sugiyama , Akira Matsumura , Kazuhiro Yamamoto

We analyze the response of a complex quantum-mechanical system (e. g., a quantum dot) to a time-dependent perturbation. Assuming the dot energy spectrum and the perturbation to be described by the Gaussian Orthogonal Ensemble of random…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 D. M. Basko , M. A. Skvortsov , V. E. Kravtsov

We analyze dephasing in single and double quantum dot systems. The decoherence is introduced by the B\"{u}ttiker model with current conserving fictitious voltage leads connected to the dots. By using the non-equilibrium Green function…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Junren Shi , Zhongshui Ma , X. C. Xie

We report the first theoretical estimate of the nuclear-spin dephasing time T_2 owing to the spin interaction with the two-dimensional electron gas, when the latter is in the integer quantum Hall state, in a two-dimensional heterojunction…

Mesoscale and Nanoscale Physics · Physics 2010-09-22 D. Mozyrsky , V. Privman , I. D. Vagner

Cooperative effects in the loss (the amplitude damping) and decoherence (the phase damping) of the qubits (two-state quantum systems) due to the inevitable coupling to the same environment are investigated. It is found that the qubits…

Quantum Physics · Physics 2007-05-23 Lu-Ming Duan , Guang-Can Guo

We study the symmetry properties in the dynamics of quantum correlations for two-qubit systems in one-sided noisy channels, with respect to a switch in the location of noise from one qubit to the other. We consider four different channel…

Quantum Physics · Physics 2017-08-25 Henri Lyyra , Göktuğ Karpat , Chuan-Feng Li , Guang-Can Guo , Jyrki Piilo , Sabrina Maniscalco

Resonant tunneling through identical potential barriers is a textbook problem in quantum mechanics. Its solution yields total transparency (100% tunneling) at discrete energies. This dramatic phenomenon results from coherent interference…

Mesoscale and Nanoscale Physics · Physics 2015-06-25 Daniel Rohrlich , Oren Zarchin , Moty Heiblum , Diana Mahalu , Vladimir Umansky

This article presents a comprehensive study of the impact of decoherence on the average correlation for pure quantum states. We explore two primary mechanisms of decoherence: phase damping and amplitude damping, each having distinct effects…

Quantum Physics · Physics 2024-03-19 A. M. Silva

Recent studies reveal that a double-quantum-dot system hosting more than two electrons may be superior in certain aspects as compared to the traditional case in which only two electrons are confined (a singlet-triplet qubit). We study the…

Mesoscale and Nanoscale Physics · Physics 2023-01-13 Guanjie He , Guo Xuan Chan , Xin Wang

The pairwise entanglement of an arbitrary atomic pair randomly extracted from a laser-driven dense multiqubit sample in the presence of quantum dissipation due to spontaneous emission is considered. The dipole-dipole interaction between the…

Quantum Physics · Physics 2015-05-14 M. Macovei , J. Evers , C. H. Keitel

As an alternative to Buttiker's dephasing lead model, we examine a dephasing stub. Both models are phenomenological ways to introduce decoherence in chaotic scattering by a quantum dot. The difference is that the dephasing lead opens up the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 C. W. J. Beenakker , B. Michaelis

We theoretically study measurement induced-dephasing of a superconducting qubit in the circuit QED architecture and compare the results to those obtained experimentally by Schuster {\it et al.}, [Phys. Rev. Lett. 94, 123602 (2005)]. Strong…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Jay Gambetta , Alexandre Blais , D. I. Schuster , A. Wallraff , L. Frunzio , J. Majer , M. H. Devoret , S. M. Girvin , R. J. Schoelkopf

A quantum system interacting with its environment is subject to dephasing which ultimately destroys the information it holds. Using a superconducting qubit, we experimentally show that this dephasing has both dynamic and geometric origins.…

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