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We investigate hyperfine-induced decoherence in a triangular spin-cluster for different qubit encodings. Electrically controllable eigenstates of spin chirality (C_z) show decoherence times that approach milliseconds, two orders of…

Mesoscale and Nanoscale Physics · Physics 2015-06-05 Filippo Troiani , Dimitrije Stepanenko , Daniel Loss

Spin defect centers with long quantum coherence times ($T_2$) are key solid-state platforms for a variety of quantum applications. Recently, cluster correlation expansion (CCE) techniques have emerged as a powerful tool to simulate the…

The central spin decoherence problem has been researched for over 50 years in the context of both nuclear magnetic resonance and electron spin resonance. Until recently, theoretical models have employed phenomenological stochastic…

Mesoscale and Nanoscale Physics · Physics 2012-08-03 Wayne M. Witzel , Malcolm S. Carroll , Lukasz Cywinski , S. Das Sarma

The clock transitions (CTs) of central spins have long coherence times because their frequency fluctuations vanish in the linear order of external field noise (such as Overhauser fields from nuclear spin baths). Therefore, CTs are useful…

Quantum Physics · Physics 2021-01-04 Geng-Li Zhang , Wen-Long Ma , Ren-Bao Liu

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

Optically addressable molecular triplet spins provide a chemically tunable platform for quantum application, but their coherence is often limited by interactions with surrounding spin baths. Here we demonstrate controlled suppression of…

We perform Ramsey spectroscopy on the ground state of ultra-cold 87Rb atoms magnetically trapped on a chip in the Knudsen regime. Field inhomogeneities over the sample should limit the 1/e contrast decay time to about 3 s, while decay times…

A pair of coupled dots with one electron in each dot can provide improvements in spin coherence, particularly at an electrical bias called the sweet spot, but few measurements have been performed on self-assembled dots in this regime. Here,…

Mesoscale and Nanoscale Physics · Physics 2022-02-17 Kha X. Tran , Allan S. Bracker , Michael K. Yates , Joel Q. Grim , Samuel G. Carter

Spin decoherence poses a significant challenge in molecular magnets, with the nuclear spin bath serving as a prominent source. Intriguingly, spin qubits at the clock transition exhibit remarkable insensitivity to the surrounding nuclear…

Quantum Physics · Physics 2025-10-14 Xiao Chen , Haechan Park , Silas Hoffman , Shuanglong Liu , Hai-Ping Cheng

Long coherence times are key to the performance of quantum bits (qubits). Here, we experimentally and theoretically show that the Hahn-echo coherence time (T2) of electron spins associated with divacancy defects in 4H-SiC reaches 1.3 ms,…

Mesoscale and Nanoscale Physics · Physics 2016-10-03 Hosung Seo , Abram L. Falk , Paul V. Klimov , Kevin C. Miao , Giulia Galli , David D. Awschalom

Magnetic fluctuations caused by the nuclear spins of a host crystal are often the leading source of decoherence for many types of solid-state spin qubit. In group-IV materials, the spin-bearing nuclei are sufficiently rare that it is…

We employ a first-principles computational workflow to screen for optically accessible, high-spin point defects in wide band gap two-dimensional (2D) crystals. Starting from an initial set of 5388 point defects, comprising both intrinsic…

Materials Science · Physics 2023-06-07 A. Sajid , F. Nilsson , S. Manti , F. Bertoldo , J. J. Mortensen , K. S. Thygesen

We theoretically study the nuclear spin induced decoherence of a quantum dot in Si that is confined at a SiGe interface. We calculate decoherence time dependence on $^{73}$Ge in the barrier layer to evaluate the importance of Ge as well as…

Mesoscale and Nanoscale Physics · Physics 2012-05-15 Wayne M. Witzel , Rajib Rahman , Malcolm S. Carroll

The loss of information about the relative phase between two quantum states, known as decoherence, strongly limits resolution in electron paramagnetic spectroscopy and hampers the use of molecules for quantum information processing. At low…

Quantum Physics · Physics 2025-04-28 Conor Ryan , Valerio Briganti , Cathal Hogan , Mark O'Neill , Alessandro Lunghi

Silicon is undoubtedly one of the most promising semiconductor materials for spin-based information processing devices. Its highly advanced fabrication technology facilitates the transition from individual devices to large-scale processors,…

We have evaluated hyperfine-induced electron spin dynamics for two electrons confined to a double quantum dot. Our quantum solution accounts for decay of a singlet-triplet correlator even in the presence of a fully static nuclear spin…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 W. A. Coish , Daniel Loss

Spectral diffusion arising from $^{29}$Si nuclear spin flip-flops, known to be a primary source of electron spin decoherence in silicon, is also predicted to limit the coherence times of neutral donor nuclear spins in silicon. Here, the…

We study the decoherence of a spin in a quantum dot due to its hyperfine coupling to a randomly fluctuating bath of nuclear spins. The system is modelled by the central spin model with the spin bath initially being at infinite temperature.…

Mesoscale and Nanoscale Physics · Physics 2013-09-02 Alexandre Faribault , Dirk Schuricht

We consider here the problem of a "central spin", with spin quantum number $S \gg 1$, interacting with a set of microscopic spins. Interactions between the microscopic spins are ignored. This model describes magnetic grains or magnetic…

Condensed Matter · Physics 2016-08-31 N. V. Prokof'ev , P. C. E. Stamp

Single electron spins coupled to multiple nuclear spins provide promising multi-qubit registers for quantum sensing and quantum networks. The obtainable level of control is determined by how well the electron spin can be selectively coupled…

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