In this talk, I plan to introduce our two recent works (arXiv: 2201.00752, arXiv: 2207.01403). I will begin with briefly introducing the basic concepts of quantum error mitigation (QEM) in the era of noisy intermediate-scale quantum (NISQ) devices and a typical QEM approach, namely the quasi-probability decomposition method. I will then make comments on this method from two aspects, i.e. its powerlessness on correlated noise and the physical meaning of its sampling cost, respectively. In the remaining time, I will focus on these two issues. In our first work (arXiv: 2201.00752), we use matrix product operators (MPO) to represent the noise channel to characterize and mitigate correlated noise in quantum circuits. As for the second work (arXiv:2207.01403), we find that the physical implementability, which is the sampling cost of implementing the noise inverse, is a good characterization of the decoherence effects.
Yuchen Guo is an undergraduate student in the Department of Physics, Tsinghua University, under the supervision of Prof. Shuo Yang. His major research interests include quantum entanglement, quantum error mitigation, and tensor networks.