Quantum-Dot Spin Qubit and Hyperfine Interaction

Klauser, D.; Coish, W. A.; Loss, Daniel

doi:10.1007/978-3-540-38235-5_2

Cited by 12 publications

(24 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(19) and approximated in the cluster expansion by Eq. (41), are the A n , b nm , and I n (nuclear spin magnitude) values.…”

Section: Calculations and Resultsmentioning

confidence: 99%

“…At this point, we will develop the rigorous mathematical formalism that relates the idea of simultaneous, independent nuclear processes contributing to the Hahn echo directly to our mathematical expression [Eq. (19)] for the Hahn echo. We will decompose Eq.…”

Section: B Mathematically Formalized Cluster Expansionmentioning

confidence: 99%

“…It will be useful to generalize this by defining v S (τ ) to be the solution to the Hahn echo, v E (τ ) [Eq. (19)], when only including the nuclei in some set S. We will use v ′ C (τ ) to represent the contribution from cluster C. Appendix B proves that the cluster contributions are independent of each other in a way that allows for the following decomposition of v S (τ ):…”

Section: Decomposing Into Cluster Contributionsmentioning

confidence: 99%

“…(17)] in Eq. (19) and collecting all distributed terms of the desired order in τ . One can additionally expand e −H n /kB T , from Eq.…”

Section: Algebraic Expansionmentioning

confidence: 99%

See 3 more Smart Citations

Quantum theory for electron spin decoherence induced by nuclear spin dynamics in semiconductor quantum computer architectures: Spectral diffusion of localized electron spins in the nuclear solid-state environment

2006

View full text Add to dashboard Cite

We consider the decoherence of a single localized electron spin due to its coupling to the lattice nuclear spin bath in a semiconductor quantum computer architecture. In the presence of an external magnetic field and at low temperatures, the dominant decoherence mechanism is the spectral diffusion of the electron spin resonance frequency due to the temporally fluctuating random magnetic field associated with the dipolar interaction induced flip-flops of nuclear spin pairs. The electron spin dephasing due to this random magnetic field depends intricately on the quantum dynamics of the nuclear spin bath, making the coupled decoherence problem difficult to solve. We provide a formally exact solution of this non-Markovian quantum decoherence problem which numerically calculates accurate spin decoherence at short times, which is of particular relevance in solid-state spin quantum computer architectures. A quantum cluster expansion method is developed, motivated, and tested for the problem of localized electron spin decoherence due to dipolar fluctuations of lattice nuclear spins. The method is presented with enough generality for possible application to other types of spin decoherence problems. We present numerical results which are in quantitative agreement with electron spin echo measurements in phosphorus doped silicon. We also present spin echo decay results for quantum dots in GaAs which differ qualitatively from that of the phosphorus doped silicon system. Our theoretical results provide the ultimate limit on the spin coherence (at least, as characterized by Hahn spin echo measurements) of localized electrons in semiconductors in the low temperature and the moderate to high magnetic field regime of interest in scalable semiconductor quantum computer architectures.

show abstract

“…(19) and approximated in the cluster expansion by Eq. (41), are the A n , b nm , and I n (nuclear spin magnitude) values.…”

Section: Calculations and Resultsmentioning

confidence: 99%

Section: B Mathematically Formalized Cluster Expansionmentioning

confidence: 99%

Section: Decomposing Into Cluster Contributionsmentioning

confidence: 99%

“…(17)] in Eq. (19) and collecting all distributed terms of the desired order in τ . One can additionally expand e −H n /kB T , from Eq.…”

Section: Algebraic Expansionmentioning

confidence: 99%

See 2 more Smart Citations

Quantum theory for electron spin decoherence induced by nuclear spin dynamics in semiconductor quantum computer architectures: Spectral diffusion of localized electron spins in the nuclear solid-state environment

2006

View full text Add to dashboard Cite

show abstract

“…2, is thus highly desirable for the realization of individual qubits. 7 Moreover, a sign change of the exciton g-factor is very desirable in quantum information processing and thus there is a strong interest in quantum dots having a zero g-factor due to the structure of the dot. To investigate the size, shape and composition dependence of the electron, hole and exciton g-factor, theoretical investigations using the k·p approximation 8,9,10 as well as tight binding calculations 11,12 have been performed on InAs/GaAs dots.…”

Section: Introductionmentioning

confidence: 99%

Size-dependent excitongfactor in self-assembled InAs/InP quantum dots

et al. 2009

View full text Add to dashboard Cite

We have studied the size dependence of the exciton g-factor in self-assembled InAs/InP quantum dots. Photoluminescence measurements on a large ensemble of these dots indicate a multimodal height distribution. Cross-sectional Scanning Tunneling Microscopy measurements have been performed and support the interpretation of the macro photoluminescence spectra. More than 160 individual quantum dots have systematically been investigated by analyzing single dot magnetoluminescence between 1200 nm and 1600 nm. We demonstrate a strong dependence of the exciton g-factor on the height and diameter of the quantum dots, which eventually gives rise to a sign change of the g-factor. The observed correlation between exciton g-factor and the size of the dots is in good agreement with calculations. Moreover, we find a size dependent anisotropy splitting of the exciton emission in zero magnetic field.

show abstract

Dephasing of Quantum Bits by a Quasi-Static Mesoscopic Environment

Taylor

Lukin

2006

Quantum Inf Process

View full text Add to dashboard Cite

We examine coherent processes in a two-state quantum system that is strongly coupled to a mesoscopic spin bath and weakly coupled to other environmental degrees of freedom. Our analysis is specifically aimed at understanding the quantum dynamics of solid-state quantum bits such as electron spins in semiconductor structures and superconducting islands. The role of mesoscopic degrees of freedom with long correlation times (local degrees of freedom such as nuclear spins and charge traps) in qubit-related dephasing is discussed in terms of a quasistatic bath. A mathematical framework simultaneously describing coupling to the slow mesoscopic bath and a Markovian environment is developed and the dephasing and decoherence properties of the total system are investigated. The model is applied to several specific examples with direct relevance to current experiments.Comparisons to experiments suggests that such quasi-static degrees of freedom play an important role in current qubit implementations. Several methods of mitigating the bath-induced error are considered.

show abstract

Quantum-Dot Spin Qubit and Hyperfine Interaction

Cited by 12 publications

References 38 publications

Quantum theory for electron spin decoherence induced by nuclear spin dynamics in semiconductor quantum computer architectures: Spectral diffusion of localized electron spins in the nuclear solid-state environment

Quantum theory for electron spin decoherence induced by nuclear spin dynamics in semiconductor quantum computer architectures: Spectral diffusion of localized electron spins in the nuclear solid-state environment

Size-dependent excitongfactor in self-assembled InAs/InP quantum dots

Dephasing of Quantum Bits by a Quasi-Static Mesoscopic Environment

Contact Info

Product

Resources

About