Fermion-parity qubit in a proximitized double quantum dot
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arXiv
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| Main Authors: | , , , , , |
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| Format: | Preprint |
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2023
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| _version_ | 1866909224906260480 |
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| author | Geier, Max Souto, Rubén Seoane Schulenborg, Jens Asaad, Serwan Leijnse, Martin Flensberg, Karsten |
| author_facet | Geier, Max Souto, Rubén Seoane Schulenborg, Jens Asaad, Serwan Leijnse, Martin Flensberg, Karsten |
| contents | Bound states in quantum dots coupled to superconductors can be in a coherent superposition of states with different electron number but with the same fermion parity. Electrostatic gating can tune this superposition to a sweet spot, where the quantum dot has the same mean electric charge independent of its electron-number parity. Here, we propose to encode quantum information in the local fermion parity of two tunnel-coupled quantum dots embedded in a Josephson junction. At the sweet spot, the qubit states have zero charge dipole moment. This protects the qubit from dephasing due to charge noise acting on the potential of each dot, as well as fluctuations of the (weak) inter-dot tunneling. At weak inter-dot tunneling, relaxation is suppressed because of disjoint qubit states. On the other hand, for strong inter-dot tunneling the system is protected against noise affecting each quantum dot separately (energy level noise, dot-superconductor tunneling fluctuations, and hyperfine interactions). Finally, we describe initialization and readout as well as single-qubit and two-qubit gates by pulsing gate voltages. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2307_05678 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Fermion-parity qubit in a proximitized double quantum dot Geier, Max Souto, Rubén Seoane Schulenborg, Jens Asaad, Serwan Leijnse, Martin Flensberg, Karsten Mesoscale and Nanoscale Physics Quantum Physics Bound states in quantum dots coupled to superconductors can be in a coherent superposition of states with different electron number but with the same fermion parity. Electrostatic gating can tune this superposition to a sweet spot, where the quantum dot has the same mean electric charge independent of its electron-number parity. Here, we propose to encode quantum information in the local fermion parity of two tunnel-coupled quantum dots embedded in a Josephson junction. At the sweet spot, the qubit states have zero charge dipole moment. This protects the qubit from dephasing due to charge noise acting on the potential of each dot, as well as fluctuations of the (weak) inter-dot tunneling. At weak inter-dot tunneling, relaxation is suppressed because of disjoint qubit states. On the other hand, for strong inter-dot tunneling the system is protected against noise affecting each quantum dot separately (energy level noise, dot-superconductor tunneling fluctuations, and hyperfine interactions). Finally, we describe initialization and readout as well as single-qubit and two-qubit gates by pulsing gate voltages. |
| title | Fermion-parity qubit in a proximitized double quantum dot |
| topic | Mesoscale and Nanoscale Physics Quantum Physics |
| url | https://arxiv.org/abs/2307.05678 |