论文标题
通过凸优化对量子状态和过程的真实实验重建
True experimental reconstruction of quantum states and processes via convex optimization
论文作者
论文摘要
我们使用受约束的凸优化（CCO）方法在实验中表征任意量子状态和在两Q量的NMR量子信息处理器上的未知量子过程。量子状态和量子过程断层扫描的标准协议基于线性反转，这通常会导致非物理密度矩阵，从而导致无效的过程矩阵。另一方面，CCO方法会产生物理上有效的密度矩阵和过程矩阵，与标准方法相比，富达度显着提高。借助半明确编程（SDP）协议解决了约束量化问题。我们使用CCO方法来估计KRAUS操作员，并在由于疏离引起的错误而表征门。然后，我们假设Markovian系统动力学，并将Lindblad Master方程与CCO方法结合使用，以完全表征NMR Qubits中存在的噪声过程。
We use a constrained convex optimization (CCO) method to experimentally characterize arbitrary quantum states and unknown quantum processes on a two-qubit NMR quantum information processor. Standard protocols for quantum state and quantum process tomography are based on linear inversion, which often result in an unphysical density matrix and hence an invalid process matrix. The CCO method on the other hand, produces physically valid density matrices and process matrices, with significantly improved fidelity as compared to the standard methods. The constrainedoptimization problem is solved with the help of a semi-definite programming (SDP) protocol. We use the CCO method to estimate the Kraus operators and characterize gates in the presence of errors due to decoherence. We then assume Markovian system dynamics and use a Lindblad master equation in conjunction with the CCO method to completely characterize the noise processes present in the NMR qubits.
