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Electron spins in quantum dots under coherent control exhibit a number of novel feedback processes. Here, we present experimental and theoretical evidence of a feedback process between nuclear spins and a single electron spin in a single…

We demonstrate a new method for projective single-shot measurement of two electron spin states (singlet versus triplet) in an array of gate-defined lateral quantum dots in GaAs. The measurement has very high fidelity and is robust with…

Long coherence times rank among the most important performance measures for many different types of quantum technology. In NV centers of diamond, the nuclear spins provide particularly long dephasing times. However, since initialization and…

Quantum Physics · Physics 2025-05-30 Jingfu Zhang , Swathi S. Hegde , Fedor Jelezko , Dieter Suter

We demonstrate control of the electron number down to the last electron in tunable few-electron quantum dots defined in catalytically grown InAs nanowires. Using low temperature transport spectroscopy in the Coulomb blockade regime we…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 C. Fasth , A. Fuhrer , L. Samuelson , Vitaly N. Golovach , Daniel Loss

We demonstrate a coherent spin shuttle through a GaAs/AlGaAs quadruple-quantum-dot array. Starting with two electrons in a spin-singlet state in the first dot, we shuttle one electron over to either the second, third or fourth dot. We…

Mesoscale and Nanoscale Physics · Physics 2019-08-02 T. Fujita , T. A. Baart , C. Reichl , W. Wegscheider , L. M. K. Vandersypen

We theoretically investigate the influence of the fluctuating Overhauser field on the spin of an electron confined to a quantum dot (QD). The fluctuations arise from nuclear angular momentum being exchanged between different nuclei via the…

Mesoscale and Nanoscale Physics · Physics 2014-05-07 Erik Welander , Evgeny Chekhovich , Alexander Tartakovskii , Guido Burkard

The decoherence of mixed electron-nuclear spin qubits is a topic of great current importance, but understanding is still lacking: while important decoherence mechanisms for spin qubits arise from quantum spin bath environments with slow…

Mesoscale and Nanoscale Physics · Physics 2015-05-26 S. J. Balian , Gary Wolfowicz , John J. L. Morton , T. S. Monteiro

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

Extending the coherence lifetime of a qubit is central to the implementation and deployment of quantum technologies, particularly in the solid-state where various noise sources intrinsic to the material host play a limiting role. Here, we…

Quantum Physics · Physics 2023-07-03 Carlos A. Meriles , Pablo R. Zangara , Daniela Pagliero

This review describes the physics of spins in quantum dots containing one or two electrons, from an experimentalist's viewpoint. Various methods for extracting spin properties from experiment are presented, restricted exclusively to…

Mesoscale and Nanoscale Physics · Physics 2011-11-09 R. Hanson , L. P. Kouwenhoven , J. R. Petta , S. Tarucha , L. M. K. Vandersypen

Unitary control of qudits can improve the collective spin squeezing of an atomic ensemble. Preparing the atoms in a state with large quantum fluctuations in magnetization strengthens the entangling Faraday interaction. The resulting…

Quantum Physics · Physics 2013-05-30 Leigh M. Norris , Collin M. Trail , Poul S. Jessen , Ivan H. Deutsch

Spin is a fundamental property of all elementary particles. Classically it can be viewed as a tiny magnetic moment, but a measurement of an electron spin along the direction of an external magnetic field can have only two outcomes: parallel…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 J. M. Elzerman , R. Hanson , L. H. Willems van Beveren , B. Witkamp , L. M. K. Vandersypen , L. P. Kouwenhoven

The temperature dependence of the coherence time of hole spins confined in self-assembled (In,Ga)As/GaAs quantum dots is studied by spin mode-locking and spin echo techniques. Coherence times limited to about a \mu s are measured for…

Mesoscale and Nanoscale Physics · Physics 2014-05-13 S. Varwig , A. René , A. Greilich , D. R. Yakovlev , D. Reuter , A. D. Wieck , M. Bayer

Electron spins and photons are complementary quantum-mechanical objects that can be used to carry, manipulate and transform quantum information. To combine these resources, it is desirable to achieve the coherent coupling of a single spin…

Mesoscale and Nanoscale Physics · Physics 2015-09-15 J. J. Viennot , M. C. Dartiailh , A. Cottet , T. Kontos

Coherence, the stability of the relative phase between quantum states, lies at the heart of quantum mechanics. Applications such as precision measurement, interferometry, and quantum computation are enabled by physical systems that have…

Quantum Gases · Physics 2017-08-07 Jee Woo Park , Zoe Z. Yan , Huanqian Loh , Sebastian A. Will , Martin W. Zwierlein

We report repeated single-shot measurements of the two-electron spin state in a GaAs double quantum dot. The readout scheme allows measurement with fidelity above 90% with a 7 microsecond cycle time. Hyperfine-induced precession between…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 C. Barthel , D. J. Reilly , C. M. Marcus , M. P. Hanson , A. C. Gossard

Decoherence of a quantum system arising from its interaction with an environment is a key concept for understanding the transition between the quantum and classical world as well as performance limitations in quantum technology…

Several topics on the implementation of spin qubits in quantum dots are reviewed. We first provide an introduction to the standard model of quantum computing and the basic criteria for its realization. Other alternative formulations such as…

Mesoscale and Nanoscale Physics · Physics 2010-07-20 Robert Andrzej Żak , Beat Röthlisberger , Stefano Chesi , Daniel Loss

The quantum coherence and gate fidelity of electron spin qubits in semiconductors is often limited by noise arising from coupling to a bath of nuclear spins. Isotopic enrichment of spin-zero nuclei such as $^{28}$Si has led to spectacular…

We discuss anomalous decoherence effects at zero and finite temperatures in driven coupled quantum spin systems. By numerical simulations of the quantum master equation, it is found that the entanglement of two coupled spin qubits exhibits…

Quantum Physics · Physics 2015-06-18 Chuan-Jia Shan , Pan-Pan Wu , Wei-Wen Cheng , Ji-Bing Liu , Tang-Kun Liu
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