Any quantum state of the radiation field, sliced in small non-overlapping space-time bins is a collection of single-rail qubits, each spanning the vacuum and single-photon Fock state of a mode. Quantum logic on these qubits would enable arbitrary measurements on information-bearing light, but is hard due to the lack of strong nonlinearities. With unentangled ancilla single-rail qubits, an $8$-port interferometer and photon detection, we show any single-rail qubit measurement in the $XY$ Bloch plane is realizable with success probability $147/256$, which beats the prior-known $1/2$ limit.

翻译：任何辐射场的量子态，在非重叠的时空区间内切片后，均可视为单轨量子比特的集合，每个量子比特张成某个模式的真空态与单光子Fock态。对这些量子比特执行量子逻辑操作将能实现对承载信息光场的任意测量，但由于缺乏强非线性相互作用，这一目标难以实现。通过使用非纠缠辅助单轨量子比特、一个$8$端口干涉仪以及光子探测，我们证明了$XY$布洛赫平面上的任意单轨量子比特测量均可以$147/256$的成功概率实现，该结果超越了先前已知的$1/2$极限。