Control fidelities in isotopically natural and enriched silicon quantum dot qubits

Quantum systems must be prepared, controlled, and measured with high fidelity in order to perform complex quantum algorithms. Control fidelities have greatly improved in silicon spin qubits but state-preparation and readout fidelities have generally been poor. By operating with low electron temperatures and employing high-bandwidth cryogenic amplifiers, we demonstrate single-qubit readout visibilities $>99\mathrm{%}$, exceeding the threshold for quantum error correction. In the same device, we achieve average single-qubit control fidelities $>99.95\mathrm{%}$. Our results show that silicon spin qubits can be operated with high overall operation fidelity.Quantum systems must be prepared, controlled, and measured with high fidelity in order to perform complex quantum algorithms. Control fidelities have greatly improved in silicon spin qubits but state-preparation and readout fidelities have generally been poor. By operating with low electron temperatures and employing high-bandwidth cryogenic amplifiers, we demonstrate single-qubit readout visibilities $>99\mathrm{%}$, exceeding the threshold for quantum error correction. In the same device, we achieve average single-qubit control fidelities $>99.95\mathrm{%}$. Our results show that silicon spin qubits can be operated with high overall operation fidelity.

arXiv:2204.09551Physical Review AppliedDec 12, 202260 citations

Theoretical issues in silicon quantum dot qubits

Teck Seng Koh

Jan 1, 20120 citations

Noise-compensating pulses for electrostatically controlled silicon spin qubits

Xin Wang, F. A. Calderon-Vargas, Muhed S. Rana +3 more

We study the performance of supcode---a family of dynamically correcting pulses designed to cancel simultaneously both Overhauser and charge noise for singlet-triplet spin qubits---adapted to silicon devices with electrostatic control. We consider both natural Si and isotope-enriched Si systems, and in each case we investigate the behavior of individual gates under static noise and perform randomized benchmarking to obtain the average gate error under realistic $1/f$ noise. We find that in most cases supcode pulses offer roughly an order of magnitude reduction in gate error, and especially in the case of isotope-enriched Si, supcode yields gate operations of very high fidelity. We also develop a version of supcode that cancels the charge noise only, ``$\ensuremath{\delta}J$-supcode,'' which is particularly beneficial for isotope-enriched Si devices where charge noise dominates Overhauser noise, offering a level of error reduction comparable to the original supcode while yielding gate times that are $30%--50%$ shorter. Our results show that the supcode noise-compensating pulses provide a fast, simple, and effective approach to error suppression, bringing gate errors well below the quantum error correction threshold in principle.We study the performance of supcode---a family of dynamically correcting pulses designed to cancel simultaneously both Overhauser and charge noise for singlet-triplet spin qubits---adapted to silicon devices with electrostatic control. We consider both natural Si and isotope-enriched Si systems, and in each case we investigate the behavior of individual gates under static noise and perform randomized benchmarking to obtain the average gate error under realistic $1/f$ noise. We find that in most cases supcode pulses offer roughly an order of magnitude reduction in gate error, and especially in the case of isotope-enriched Si, supcode yields gate operations of very high fidelity. We also develop a version of supcode that cancels the charge noise only, ``$\ensuremath{\delta}J$-supcode,'' which is particularly beneficial for isotope-enriched Si devices where charge noise dominates Overhauser noise, offering a level of error reduction comparable to the original supcode while yielding gate times that are $30%--50%$ shorter. Our results show that the supcode noise-compensating pulses provide a fast, simple, and effective approach to error suppression, bringing gate errors well below the quantum error correction threshold in principle.

arXiv:1407.1555Physical Review BOct 14, 201423 citations

Optimizing fidelities of quantum dot hybrid qubits

S. N. Coppersmith

Bulletin of the American Physical SocietyMar 15, 20160 citations

High-fidelity and robust two-qubit gates for quantum-dot spin qubits in silicon

Chia-Hsien Huang, Chih Hwan Yang, Chien-Chang Chen +2 more

A two-qubit controlled-not (cnot) gate, realized by a controlled-phase (C-phase) gate combined with single-qubit gates, has been experimentally implemented recently for quantum-dot spin qubits in isotopically enriched silicon, a promising solid-state system for practical quantum computation. In the experiments, the single-qubit gates have been demonstrated with fault-tolerant control fidelity, but the infidelity of the two-qubit C-phase gate is, primarily due to the electrical noise, still higher than the required error threshold for fault-tolerant quantum computation (FTQC). Here, by taking the realistic system parameters and the experimental constraints on the control pulses into account, we construct experimentally realizable high-fidelity cnot gates robust against electrical noise with the experimentally measured $1/{f}^{1.01}$ noise spectrum and also against the uncertainty in the interdot tunnel coupling amplitude. Our fine-tuned optimal cnot gate has about two orders of magnitude improvement in gate infidelity over the ideal C-phase gate constructed without considering any noise effect. Furthermore, within the same control framework, high-fidelity and robust single-qubit gates can also be constructed, paving the way for large-scale FTQC.A two-qubit controlled-not (cnot) gate, realized by a controlled-phase (C-phase) gate combined with single-qubit gates, has been experimentally implemented recently for quantum-dot spin qubits in isotopically enriched silicon, a promising solid-state system for practical quantum computation. In the experiments, the single-qubit gates have been demonstrated with fault-tolerant control fidelity, but the infidelity of the two-qubit C-phase gate is, primarily due to the electrical noise, still higher than the required error threshold for fault-tolerant quantum computation (FTQC). Here, by taking the realistic system parameters and the experimental constraints on the control pulses into account, we construct experimentally realizable high-fidelity cnot gates robust against electrical noise with the experimentally measured $1/{f}^{1.01}$ noise spectrum and also against the uncertainty in the interdot tunnel coupling amplitude. Our fine-tuned optimal cnot gate has about two orders of magnitude improvement in gate infidelity over the ideal C-phase gate constructed without considering any noise effect. Furthermore, within the same control framework, high-fidelity and robust single-qubit gates can also be constructed, paving the way for large-scale FTQC.

arXiv:1806.02858Physical Review AApr 4, 201919 citations

1/f

noise. We find that in most cases supcode pulses offer roughly an order of magnitude reduction in gate error, and especially in the case of isotope-enriched Si, supcode yields gate operations of very high fidelity. We also develop a version of supcode that cancels the charge noise only, ``$\ensuremath{\delta}J$-supcode,'' which is particularly beneficial for isotope-enriched Si devices where charge noise dominates Overhauser noise, offering a level of error reduction comparable to the original supcode while yielding gate times that are

30%--50%

shorter. Our results show that the supcode noise-compensating pulses provide a fast, simple, and effective approach to error suppression, bringing gate errors well below the quantum error correction threshold in principle.

1/{f}^{1.01}

noise spectrum and also against the uncertainty in the interdot tunnel coupling amplitude. Our fine-tuned optimal cnot gate has about two orders of magnitude improvement in gate infidelity over the ideal C-phase gate constructed without considering any noise effect. Furthermore, within the same control framework, high-fidelity and robust single-qubit gates can also be constructed, paving the way for large-scale FTQC.