tqix: A toolbox for Quantum in X: Quantum measurement, quantum tomography, quantum metrology, and others

We present an open-source computer program written in Python language for quantum measurement and related issues. In our program, quantum states and operators, including quantum gates, can be developed into a quantum-object function represented by a matrix. Build into the program are several measurement schemes, including von Neumann measurement and weak measurement. Various numerical simulation methods are used to mimic the real experiment results. We first provide an overview of the program structure and then discuss the numerical simulation of quantum measurement. We illustrate the program's performance via quantum state tomography and quantum metrology. The program is built in a general language of quantum physics and thus is widely adaptable to various physical platforms, such as quantum optics, ion traps, superconducting circuit devices, and others. It is also ideal to use in classroom guidance with simulation and visualization of various quantum systems.