A two-qubit logic gate in silicon

By Menno Veldhorst, C. Yang, J. C. Hwang, W. Huang, Juan Pablo Dehollain, J. Muhonen, S. Simmons, A. Laucht, Fay Hudson, Kohei M. Itoh and 2 more. Nature, 2014

851 citations recorded by the source corpus.

Quantum computation requires qubits that can be coupled in a scalable manner, together with universal and high-fidelity one- and two-qubit logic gates. Many physical realizations of qubits exist, including single photons, trapped ions, superconducting circuits, single defects or atoms in diamond and silicon, and semiconductor quantum dots, with single-qubit fidelities that exceed the stringent thresholds required for fault-tolerant quantum computing. Despite this, high-fidelity two-qubit gates in the solid state that can be manufactured using standard lithographic techniques have so far been limited to superconducting qubits, owing to the difficulties of coupling qubits and dephasing in semiconductor systems. Here we present a two-qubit logic gate, which uses single spins in isotopically enriched silicon and is realized by performing single- and two-qubit operations in a quantum dot system using the exchange interaction, as envisaged in the Loss–DiVincenzo proposal. We realize CNOT gates via controlled-phase operations combined with single-qubit operations. Direct gate-voltage control provides single-qubit addressability, together with a switchable exchange interaction that is used in the two-qubit controlled-phase gate. By independently reading out both qubits, we measure clear anticorrelations in the two-spin probabilities of the CNOT gate.

Subfields: Artificial Intelligence, Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/76da89fa27e8b066604aff5d9014b6b3bbe226a9

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Citations in the corpus

Silicon CMOS architecture for a spin-based quantum computer (2016, background): “Starting from the (0,2) singlet ground state, qubit initialization is obtained by adiabatically moving to the (1,1) state, which results in a spin-down state in the dot with the larger g-factor [20].”
Quantum computing: A taxonomy, systematic review and future directions (2020, neutral): “[60]             R Mizuta et al.”
Chip-to-chip quantum teleportation and multi-photon entanglement in silicon (2019, neutral): “Exploiting semiconductor fabrication techniques, natural carriers of quantum information such as atoms, electrons, and photons can be embedded in scalable integrated devices [1–3].”
Cryo-CMOS Circuits and Systems for Quantum Computing Applications (2018, background): “Only some (de)multiplexing, such as frequency [17], [32] or time [33] multiplexing, is envisioned at the quantum-processor temperature to reduce the number of interconnects.”
Review of performance metrics of spin qubits in gated semiconducting nanostructures (2021, background): “[256, 264, 284] could be acknowledged to have reached the “processor” level, and only in the most recent one the fidelities where high enough to run the most elementary quantum circuits.”
Qubits made by advanced semiconductor manufacturing (2021, background): “With the Rabi decay being dominated by low-frequency noise, the present combination of T ∗ 2 and Rabi frequency should allow an even higher fidelity [6, 23, 29].”
A programmable two-qubit quantum processor in silicon (2017, methodology): “Gate fidelity and coherence of an electron spin in an Si/SiGe q uantum dot 218 with micromagnet.Proc. Natl. Acad. Sci. 113, 11738–11743 (2016). 219 22.”