Single-mode quantum metrology enhanced by approximate quantum error correction

Quantum metrology makes use of quantum effects to achieve high measurement precision beyond classical limitations. However, in practice, quantum probe systems are sensitive to noise, restricting the attainable enhancement through quantum effects. In this talk, we will present our recent efforts in quantum metrology via a bosonic mode. We first show the principle of the single-mode bosonic quantum metrology with a superconducting circuit and demonstrate an unconditional phase estimation approaching the Heisenberg limit (HL). By preparing the superpositions of Fock states (|0>+|N>) up to N=12, we realize a 9.1 dB improvement over the SNL at N=12, which is only 1.7 dB away from the HL[1]. Then, we further extend our experimental architecture to fight against practical decoherence by introducing quantum error correction (QEC) technique to the bosonic mode. By an approximate QEC together with a trajectory method, we realize a photon-number detection sensitivity on the order of 10^-4HZ^-1/2, achieving an enhancement over the case without any QEC technique. Our results reveal the considerable potential of bosonic QEC in quantum metrology applications.
[1] W. Wang, et. al.,“Heisenberg-limited single-mode quantum metrology in a superconducting circuit,” Nat. Commun. 10, 4382 (2019)