Abstract
We theoretically propose and experimentally implement a method of measuring a qubit by driving it close to the frequency of a dispersively coupled bosonic mode. The separation of the bosonic states corresponding to different qubit states begins essentially immediately at maximum rate, leading to a speedup in the measurement protocol. Also the bosonic mode can be simultaneously driven to optimize measurement speed and fidelity. We experimentally test this measurement protocol using a superconducting qubit coupled to a resonator mode. For a certain measurement time, we observe that the conventional dispersive readout yields close to 100% higher average measurement error than our protocol. Finally, we use an additional resonator drive to leave the resonator state to vacuum if the qubit is in the ground state during the measurement protocol. This suggests that the proposed measurement technique may become useful in unconditionally resetting the resonator to a vacuum state after the measurement pulse.
| Original language | English |
|---|---|
| Article number | 080503 |
| Number of pages | 7 |
| Journal | Physical Review Letters |
| Volume | 122 |
| Issue number | 8 |
| DOIs | |
| Publication status | Published - 25 Feb 2019 |
| MoE publication type | A1 Journal article-refereed |
Funding
This research was financially supported by European Research Council under Grant No.A681311 (QUESS) and Marie Sklodowska-Curie Grant No.A795159; by Academy of Finland under its Centres of Excellence Program Grants No.A312300 and NoA312059 and under other Grants No.A265675, No.A305237, No.A305306, No.A308161, No.A312300, No.A314302, No.316551, and No.A319579; Finnish Cultural Foundation, the Jane and Aatos Erkko Foundation, Vilho, Yrjo and Kalle Vaisala Foundation, and the Technology Industries of Finland Centennial Foundation.
Keywords
- quantum computation
- superconducting qubits
- quantum measurements
- quantum sensing
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