Compressed Optimization of Device Architectures for Semiconductor Quantum Devices

Frees, Adam; Gamble, John King; Ward, Daniel R.; Blume-Kohout, Robin; Eriksson, M. A.; Friesen, Mark; Coppersmith, S. N.

doi:10.1103/physrevapplied.11.024063

Cited by 10 publications

(5 citation statements)

References 46 publications

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“…We now show that this effect primarily results from lateral shifts of the quantum dots during a barrier-gate pulse. We have self-consistently calculated the electron density and potential of our device in COMSOL using the Thomas-Fermi approximation [47]. Our simulation replicates the behavior of the physical device with high fidelity.…”

Section: Effect Of Position Shifts On Exchange Couplingmentioning

confidence: 97%

Coherent Multispin Exchange Coupling in a Quantum-Dot Spin Chain

et al. 2020

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Heisenberg exchange coupling between neighboring electron spins in semiconductor quantum dots provides a powerful tool for quantum information processing and simulation. Although so far unrealized, extended Heisenberg spin chains can enable long-distance quantum information transfer and the generation of nonequilibrium quantum states. In this work, we implement simultaneous, coherent exchange coupling between all nearest-neighbor pairs of spins in a quadruple quantum dot. The main challenge in implementing simultaneous exchange couplings is the nonlinear and nonlocal dependence of the exchange couplings on gate voltages. Through a combination of electrostatic simulation and theoretical modeling, we show that this challenge arises primarily due to lateral shifts of the quantum dots during gate pulses. Building on this insight, we develop two models that can be used to predict the confinement gate voltages for a desired set of exchange couplings. Although the model parameters depend on the number of exchange couplings desired (suggesting that effects in addition to lateral wave-function shifts are important), the models are sufficient to enable simultaneous and independent control of all three exchange couplings in a quadruple quantum dot. We demonstrate two-, three-, and four-spin exchange oscillations, and our data agree with simulations.

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Section: Effect Of Position Shifts On Exchange Couplingmentioning

confidence: 97%

Coherent Multispin Exchange Coupling in a Quantum-Dot Spin Chain

et al. 2020

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“…We now show that this effect primarily results from lateral shifts of the quantum dots during a barrier-gate pulse. We have self-consistently calculated the electron density and potential of our device in COMSOL using the Thomas-Fermi approximation [38]. Figure 2(a) shows the potential associated with dots 2 and 3 tuned to singleoccupancy as a function of the barrier voltage B 2 .…”

Section: The Effect Of Position Shifts On Exchangementioning

confidence: 99%

Coherent multi-spin exchange coupling in a quantum-dot spin chain

Qiao,

Kandel,

Deng

et al. 2020

Preprint

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Heisenberg exchange coupling between neighboring electron spins in semiconductor quantum dots provides a powerful tool for quantum information processing and simulation. Although so far unrealized, extended Heisenberg spin chains can enable long-distance quantum information transfer and the generation of non-equilibrium quantum states. In this work, we implement simultaneous, coherent exchange coupling between all nearest-neighbor pairs of spins in a quadruple quantum dot. The main challenge in implementing simultaneous exchange is the nonlinear and nonlocal dependence of the exchange couplings on gate voltages. Through a combination of electrostatic simulation and theoretical modeling, we show that this challenge arises primarily due to lateral shifts of the quantum dots during gate pulses. Building on this insight, we develop two models, which can be used to predict the confinement gate voltages for a desired set of exchange couplings. We achieve simultaneous and independent control of all three exchange couplings in a quadruple quantum dot. We demonstrate two-, three-, and four-spin exchange oscillations, and our data agree with simulations.

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“…Another way to approach this problem is to design qubits where crosstalk is reduced, and each gate more directly controls a qubit property in a known way, which has been a benefit of the overlapping gate structure [18,37,139,140]. Simulations have also been used to aid in designing such devices [141].…”

Section: Scalingmentioning

confidence: 99%

Quantum Dots / Spin Qubits

Harvey

2022

Preprint

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Spin qubits in semiconductor quantum dots represent a prominent family of solidstate qubits in the effort to build a quantum computer. They are formed when electrons or holes are confined in a static potential well in a semiconductor, giving them a quantized energy spectrum. The simplest spin qubit is a single electron spin located in a quantum dot, but many additional varieties have been developed, some containing multiple spins in multiple quantum dots, each of which has different benefits and drawbacks. While these spins act as simple quantum systems in many ways, they also experience complex effects due to their semiconductor environment. They can be controlled by both magnetic and electric fields depending on their configuration and are therefore dephased by magnetic and electric field noise, with different types of spin qubits having different control mechanisms and noise susceptibilities. While initial experiments were primarily performed in gallium arsenide (GaAs) based materials, silicon qubits have developed substantially and research on qubits in metal-oxide-semiconductor (Si-MOS), silicon/silicon germanium (Si/SiGe) heterostructures, and donors in silicon is also being pursued. An increasing number of spin qubit varieties have attained error rates that are low enough to be compatible with quantum error correction for single-qubit gates and two-qubit gates have been performed in several with success rates, or fidelities, of 90-95%.

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Compressed Optimization of Device Architectures for Semiconductor Quantum Devices

Cited by 10 publications

References 46 publications

Coherent Multispin Exchange Coupling in a Quantum-Dot Spin Chain

Coherent Multispin Exchange Coupling in a Quantum-Dot Spin Chain

Coherent multi-spin exchange coupling in a quantum-dot spin chain

Quantum Dots / Spin Qubits

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