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Rapid progress in semiconductor spin qubits has enabled experimental demonstrations of a two-qubit logic gate. Understanding spin decoherence in a two-qubit logic gate is necessary for optimal qubit operation. We study spin decoherence due…

Mesoscale and Nanoscale Physics · Physics 2018-11-29 Peihao Huang , Neil M. Zimmerman , Garnett W. Bryant

Coherent links between qubits separated by tens of micrometers are expected to facilitate scalable quantum computing architectures for spin qubits in electrically-defined quantum dots. These links create space for classical on-chip control…

Mesoscale and Nanoscale Physics · Physics 2023-09-25 A. M. J. Zwerver , S. V. Amitonov , S. L. de Snoo , M. T. Mądzik , M. Russ , A. Sammak , G. Scappucci , L. M. K. Vandersypen

We analyze decoherence of an electron in a double-dot due to the interaction with acoustic phonons. For large tunneling rates between the quantum dots, the main contribution to decoherence comes from the phonon emission relaxation…

Quantum Physics · Physics 2007-05-23 L. Fedichkin , A. Fedorov

Despite the importance of isotopically purified samples in current experiments, there have been few corresponding studies of spin qubit decoherence using full quantum bath calculations. Isotopic purification eliminates the well-studied…

Quantum Physics · Physics 2016-01-06 J. E. Lang , R. Guichard , S. J. Balian , T. S. Monteiro

Exchange-only spin qubits hosted in $^{28}$Si-based triple quantum dots do not suffer from decoherence caused by randomly fluctuating nuclear-spin ensembles and can be relatively robust against electrical noise when operated at a sweet…

Mesoscale and Nanoscale Physics · Physics 2018-12-18 Arnau Sala , Jeroen Danon

A scheme based on Coherent Tunneling by Adiabatic Passage (CTAP) of exchange-only spin qubit quantum states in a linearly arranged double quantum dot chain is demonstrated. Logical states for the qubit are defined by adopting the spin state…

Quantum Physics · Physics 2018-09-05 E. Ferraro , M. De Michielis , M. Fanciulli , E. Prati

We theoretically consider coherence times for spins in two quantum computer architectures, where the qubit is the spin of an electron bound to a P donor impurity in Si or within a GaAs quantum dot. We show that low temperature decoherence…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Rogerio de Sousa , S. Das Sarma

We have studied spin-flip transitions between Zeeman sublevels in GaAs electron quantum dots. Several different mechanisms which originate from spin-orbit coupling are shown to be responsible for such processes. It is shown that…

Mesoscale and Nanoscale Physics · Physics 2016-08-31 Alexander V. Khaetskii , Yuli V. Nazarov

Quantum information transport over micron to millimeter scale distances is critical for the operation of practical quantum processors based on spin qubits. One method of achieving a long-range interaction is by coherent electron spin…

Mesoscale and Nanoscale Physics · Physics 2024-12-18 Natalie D. Foster , Jacob D. Henshaw , Martin Rudolph , Dwight R. Luhman , Ryan M. Jock

Long-range quantum communication for spin qubits is an important open problem. Here we study decoherence of an electron spin qubit that is being transported in a moving quantum dot. We focus on spin decoherence due to spin-orbit interaction…

Mesoscale and Nanoscale Physics · Physics 2013-08-12 Peihao Huang , Xuedong Hu

We study electron-phonon interaction induced decoherence between two-electron singlet and triplet states in a semiconductor double quantum dot using a spin-boson model. We investigate the onset and time evolution of this dephasing, and…

Mesoscale and Nanoscale Physics · Physics 2015-05-20 Xuedong Hu

Shuttling spins with high fidelity is a key requirement to scale up semiconducting quantum computers, enabling qubit entanglement over large distances and favoring the integration of control electronics on-chip. To decouple the spin from…

Mesoscale and Nanoscale Physics · Physics 2024-06-10 Stefano Bosco , Ji Zou , Daniel Loss

We study theoretically spin relaxation during phonon-assisted tunneling of a single electron in self-assembled InAs/GaAs quantum-dot molecules formed by vertically stacked dots. We find that the spin-flip tunneling rate may be as high as 1%…

Mesoscale and Nanoscale Physics · Physics 2021-06-23 Michał Gawełczyk , Krzysztof Gawarecki

We consider a single electron in a 1D quantum dot with a static slanting Zeeman field. By combining the spin and orbital degrees of freedom of the electron, an effective quantum two-level (qubit) system is defined. This pseudo-spin can be…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Yasuhiro Tokura , Wilfred G. van der Wiel , Toshiaki Obata , Seigo Tarucha

We demonstrate improved operation of exchange-coupled semiconductor quantum dots by substantially reducing the sensitivity of exchange operations to charge noise. The method involves biasing a double-dot symmetrically between the…

Spin-orbit coupling is ubiquitous in quantum dot quantum computing architectures, and makes spin qubits susceptible to charge noise. We derive a Hamiltonian describing the effect of spin-orbit and noise on a single-spin qubit in a quantum…

Mesoscale and Nanoscale Physics · Physics 2014-11-14 Adam Bermeister , Daniel Keith , Dimitrie Culcer

We review progress on the spintronics proposal for quantum computing where the quantum bits (qubits) are implemented with electron spins. We calculate the exchange interaction of coupled quantum dots and present experiments, where the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Hans-Andreas Engel , L. P. Kouwenhoven , Daniel Loss , C. M. Marcus

Spin qubits in semiconductor quantum dots are one of the promizing devices to realize a quantum processor. A better knowledge of the noise sources affecting the coherence of such a qubit is therefore of prime importance. In this work, we…

Mesoscale and Nanoscale Physics · Physics 2023-04-04 Baker Shalak , Christophe Delerue , Yann-Michel Niquet

The effects of a nearby two-level charge fluctuator on a double-dot two-spin qubit are studied theoretically. Assuming no direct tunneling between the charge fluctuator and the qubit quantum dots, the Coulomb couplings between the qubit…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 Guy Ramon , Xuedong Hu

We study three-electron-spin decoherence in a semiconductor triple quantum dot with a linear geometry. The three electron spins are coupled by exchange interactions J_{12} and J_{23}, and we clarify inhomogeneous and homogeneous dephasing…

Mesoscale and Nanoscale Physics · Physics 2014-07-23 Jo-Tzu Hung , Jianjia Fei , Mark Friesen , Xuedong Hu