基于超导电路量子电动力学（QED）系统中的弱测量，本项目将研究几个量子物理新概念和新技术，它们在量子信息领域有潜在的应用价值。1) 完善电路QED系统中的量子弱测量理论，考虑包括Purcell效应在内的若干复杂因素的影响；建立多个量子比特联合测量的量子贝叶斯公式。 2) 澄清奇异量子弱值的本质；超越“坏腔”“弱耦合”近似，建立电路QED系统中更一般的量子弱值表达式，为实际应用奠定基础。 3) 利用得到的量子弱值公式，研究电路QED系统中量子态的直接测量方法（一种新的波函数成像技术）。 4) 利用电路QED系统中的量子贝叶斯公式，研究“过去量子态”（Past Quantum State）的物理内涵和分析技术，期望得到比常规方法更好的结果。 5) 结合电路QED系统中的实际测量情形，研究单比特叠加态、多比特纠缠态和微腔光场态的量子smoothing技术，开发量子smoothing的潜在应用。

Based on weak measurement in the circuit quantum eletrodynamics (QED) system, this project is aimed to investigate several important and new quantum concepts and technigues: (i) improve the theory of quantum weak measurement in terms of quantum Bayesian formulation, construct Bayesian formula for multi-qubits measurement and include such as the Purcell effect induced nonidealities; (ii) clarify the physical origin of anomalous weak value and obtain weak-value expression beyond the limits of bad-cavity and weak coupling; (iii) explore the weak-value-based new method of direct measuerement for quantum states; (iv) study the past quantum state and its application in circuit-QED system; (v) develop quantum smoothing technique for the circuit QED single-qubit, multi-qubits and cavity-field states.