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A multi-slit interference experiment, with which-way detectors, in the presence of environment induced decoherence, is theoretically analyzed. The effect of environment is modeled via a coupling to a bath of harmonic oscillators. Through an…

Quantum Physics · Physics 2018-11-02 Anu Venugopalan , Sandeep Mishra , Tabish Qureshi

In this paper we study the decoherence and purity of a driven solid-state qubit in the Ohmic bath by using the method based on the master equation. At first, instead of solving the master equation we investigate the coefficients of the…

Quantum Physics · Physics 2009-11-13 Zhi-Qiang Li , Xian-Ting Liang

Electron spins confined in quantum dots are an attractive system to realize high-fidelity qubits owing to their long coherence time. With the prolonged spin coherence time, however, the control fidelity can be limited by systematic errors…

Mesoscale and Nanoscale Physics · Physics 2018-10-30 K. Takeda , J. Yoneda , T. Otsuka , T. Nakajima , M. R. Delbecq , G. Allison , Y. Hoshi , N. Usami , K. M. Itoh , S. Oda , T. Kodera , S. Tarucha

The decoherence rate of a quantum dot coupled to a fluctuating environment described by a normal-metal superconductor junction is considered. The density-density correlator at low frequencies constitutes the kernel which enters the…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Rodolphe Guyon , Thierry Martin , Gordey B. Lesovik

We have developed quantitative description of quantum coherent oscillations in the system of two coupled qubits in the presence of weak decoherence that in general can be correlated between the two qubits. It is shown that in the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Kristian Rabenstein , Dmitri V. Averin

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, applied electric fields can be used to…

Mesoscale and Nanoscale Physics · Physics 2008-01-09 Pablo San-Jose , Burkhard Scharfenberger , Gerd Schön , Alexander Shnirman , Gergely Zarand

We study a pair of capacitively coupled singlet-triplet spin qubits. We characterize the two-qubit decoherence through two complementary measures, the decay time of coupled-qubit oscillations and the fidelity of entangled state preparation.…

Mesoscale and Nanoscale Physics · Physics 2017-10-11 Yang-Le Wu , S. Das Sarma

We analyze the decoherence induced on a single qubit by the interaction with a two-level boson system with critical internal dynamics. We explore how the decoherence process is affected by the presence of quantum phase transitions in the…

Quantum Physics · Physics 2015-05-14 A. Relano , J. M. Arias , J. Dukelsky , J. E. Garcia-Ramos , P. Perez-Fernandez

The limitations for the coherent manipulation of neutral atoms with fabricated solid state devices, so-called `atom chips', are addressed. Specifically, we examine the dominant decoherence mechanism, which is due to the magnetic noise…

Quantum Physics · Physics 2009-11-07 Carsten Henkel , Peter Kr"uger , Ron Folman , J"org Schmiedmayer

Developing fast and accurate control and readout techniques is an important challenge in quantum information processing with semiconductor qubits. Here, we study the dynamics and the coherence properties of a GaAs/AlGaAs double quantum dot…

Quantum feedback is assuming increasingly important role in quantum control and quantum information processing. In this work we analyze the application of such feedback techniques in eliminating decoherence in open quantum systems. In order…

Quantum Physics · Physics 2016-11-15 Narayan Ganesan , Tzyh Jong Tarn

We experimentally demonstrate a tunable hybrid qubit in a five-electron GaAs double quantum dot. The qubit is encoded in the (1,4) charge regime of the double dot and can be manipulated completely electrically. More importantly, dot…

Mesoscale and Nanoscale Physics · Physics 2016-03-02 Gang Cao , Hai-Ou Li , Guo-Dong Yu , Bao-Chuan Wang , Bao-Bao Chen , Xiang-Xiang Song , Ming Xiao , Guang-Can Guo , Hong-Wen Jiang , Xuedong Hu , Guo-Ping Guo

Coherent control of two-state systems is traditionally achieved by resonant pulses of specific Rabi frequency and duration, by adiabatic techniques using level crossings or delayed pulses, or by sequences of pulses with precise relative…

Quantum Physics · Physics 2019-01-23 Boyan T. Torosov , Nikolay V. Vitanov

In many realizations of electron spin qubits the dominant source of decoherence is the fluctuating nuclear spin bath of the host material. The slowness of this bath lends itself to a promising mitigation strategy where the nuclear spin bath…

Mesoscale and Nanoscale Physics · Physics 2010-11-30 Hendrik Bluhm , Sandra Foletti , Diana Mahalu , Vladimir Umansky , Amir Yacoby

Characterising the time over which quantum coherence survives is critical for any implementation of quantum bits, memories and sensors. The usual method for determining a quantum system's decoherence rate involves a suite of experiments…

We present an approach that allows quantifying decoherence processes in an open quantum system subject to external time-dependent control. Interactions with the environment are modeled by a standard bosonic heat bath. We develop two…

Mesoscale and Nanoscale Physics · Physics 2010-10-12 Dmitry Solenov , Vladimir Privman

We study the influence of the environment on an optically induced rotation of a single electron spin in a charged semiconductor quantum dot. We analyze the decoherence mechanisms resulting from the dynamical lattice response to the charge…

Mesoscale and Nanoscale Physics · Physics 2009-04-27 A. Grodecka , C. Weber , P. Machnikowski , A. Knorr

We analyze robustness of decoherence-free (DF) subspace in charge qubits when there are a local structure and non-uniformity that violate collective decoherence measurement condition. We solve master equations of up to four charge qubits…

Quantum Physics · Physics 2014-01-08 Tetsufumi Tanamoto , Shinobu Fujita

We investigate the measurement-induced dephasing of a qubit coupled with a single-mode cavity in the vacuum limit. Dephasing of the qubit state takes place through the ntanglement of the qubit and the single probe photon sent to the cavity,…

Mesoscale and Nanoscale Physics · Physics 2014-07-09 Young-Wan Kim , Kang-Ho Lee , Kicheon Kang

Decoherence is a major challenge for quantum technologies. A way to mitigate its negative impact is by employing quantum optimal control. The decoherence dynamics varies significantly based on the characteristics of the surrounding…