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The population decay due to a small opening in an otherwise closed cavity supporting chaotic classical dynamics displays a quantum correction on top of the classical exponential form, a pure manifestation of quantum coherence that acquires…

Quantum Physics · Physics 2021-05-12 Camilo Moreno , Juan-Diego Urbina

Real quantum systems couple to their environment and lose their intrinsic quantum nature through the process known as decoherence. Here we present a method for minimizing decoherence by making it energetically unfavorable. We present a…

Quantum Physics · Physics 2009-11-06 D. Bacon , K. R. Brown , K. B. Whaley

For the standard Quantum Brownian Motion (QBM) model, we point out the occurrence of simultaneous (parallel), mutually irreducible and autonomous decoherence processes. Besides the standard, one Brownian particle, we show there is at least…

Quantum Physics · Physics 2012-09-05 M. Dugic , J. Jeknic-Dugic

Ten years ago, coherent oscillations between two quantum states of a superconducting circuit differing by the presence or absence of a single Cooper pair on a metallic island were observed for the first time. This result immediately…

Mesoscale and Nanoscale Physics · Physics 2009-10-19 Vladimir E. Manucharyan , Jens Koch , Markus Brink , Leonid I. Glazman , Michel H. Devoret

Quantum coherence is a fundamental characteristic to distinguish quantum systems from their classical counterparts. Though quantum coherence persists in isolated non-interacting systems, interactions inevitably lead to decoherence, which is…

Quantum Gases · Physics 2017-11-15 Ke-Ji Chen , Ho Kwan Lau , Hon Ming Chan , Dajun Wang , Qi Zhou

In this study, we examine decoherence of qubits system coupled independently by using influence functional. We especially concentrated on the effect of qubit flip process. We examine the zero-dimensional qubit and one-dimensional qubits…

Quantum Physics · Physics 2008-09-30 Toshifumi Itakura

We show that the unitary evolution of a harmonic oscillator coupled to a two-level system can be undone by a suitable manipulation of the two-level system -- more specifically: by a quasi-instantaneous phase change. This enables us to…

Quantum Physics · Physics 2010-03-26 Giovanna Morigi , Enrique Solano , Berthold-Georg Englert , Herbert Walther

The unit of quantum information is the qubit, a vector in a two-dimensional Hilbert space. On the other hand, quantum hardware often operates in two-dimensional subspaces of vector spaces of higher dimensionality. The presence of higher…

Condensed Matter · Physics 2009-10-31 Rosario Fazio , G. Massimo Palma , Jens Siewert

We investigate the quantum phase transitions in two capacitively coupled chains of ultra-small Josephson-junctions, with emphasis on the external charge effects. The particle-hole symmetry of the system is broken by the gate voltage applied…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Mahn-Soo Choi , M. Y. Choi , Taeseung Choi , Sung-Ik Lee

Decoherence-free subspaces allow for the preparation of coherent and entangled qubits for quantum computing. Decoherence can be dramatically reduced, yet dissipation is an integral part of the scheme in generating stable qubits and…

Quantum Physics · Physics 2009-11-07 Ben Tregenna , Almut Beige , Peter L. Knight

We investigate the dynamics of coherence and entanglement of vibrating qubits. Firstly, we consider a single trapped ion qubit inside a perfect cavity and successively we use it to construct a bipartite system made of two of such…

Quantum Physics · Physics 2018-05-14 Ali Mortezapour , Ghasem Naeimi , Rosario Lo Franco

In this paper, we analyze the evolution of quantum coherence in a two-qubit system going through the amplitude damping channel. After they have gone through this channel many times, we analyze the systems with respect to the coherence of…

Quantum Physics · Physics 2017-12-29 Ming-Jing Zhao , Teng Ma , YuQuan Ma

Decoherence of a solid state based qubit can be caused by coupling to microscopic degrees of freedom in the solid. We lay out a simple theory and use it to estimate decoherence for a recently proposed superconducting persistent current…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Lin Tian , L. S. Levitov , Caspar H. van der Wal , J. E. Mooij , T. P. Orlando , S. Lloyd , C. J. P. M. Harmans , J. J. Mazo

We propose a novel platform for the study of quantum phase transitions in one dimension (1D QPT). The system consists of a specially designed chain of asymmetric SQUIDs; each SQUID contains several Josephson junctions with one junction…

Strongly Correlated Electrons · Physics 2018-12-04 M. T. Bell , B. Doucot , M. E. Gershenson , L. B. Ioffe , A. Petkovic

We revisit the problem of decoherence of a qubit centrally coupled to an interacting spin environment, here modeled by a quantum compass chain or an extended XY model in a staggered magnetic field. These two models both support distinct…

Statistical Mechanics · Physics 2017-12-22 R. Jafari , Henrik Johannesson

In order to examine whether or not the quantum phase transition of Dicke type exists in realistic systems, we revisit the model setup of the superconducting circuit QED from a microscopic many-body perspective based on the BCS theory with…

Quantum Physics · Physics 2012-04-16 D. Z. Xu , Y. B. Gao , C. P. Sun

We study the problem of environmentally-induced decoherence in a near-critical one-dimensional system of N>>1 coupled qubits. Using the Jordan-Wigner fermion representation of the qubit operators we identify the decoherence rates relevant…

Condensed Matter · Physics 2009-11-10 D. V. Khveshchenko

The evolution of a quantum system comprises two fundamental processes--continuous unitary dynamics and stochastic measurement-induced jumps. The latter are often viewed as a source of decoherence. Can two histories of such an evolution,…

Quantum Physics · Physics 2026-05-25 Parveen Kumar , Igor V. Gornyi , Yuval Gefen

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), with logical states differing by one…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Yuriy Makhlin , Gerd Schoen , Alexander Shnirman

The decoherence of quantum states defines the transition between the quantum world and classical physics. Decoherence or, analogously, quantum mechanical collapse events pose fundamental questions regarding the interpretation of quantum…

Mesoscale and Nanoscale Physics · Physics 2021-09-24 P. Bredol , H. Boschker , D. Braak , J. Mannhart