Quantum Optimal Control for Mitigating Bit-Flip, Phase-Flip, and Depolarizing Noise in Quantum Systems

Liu‐Yong Cheng, Shi-Feng 世凤 Zhang 张, Zuan 钻 Meng 孟 +2 more

We investigate the influence of a noisy environment on the remote preparation of the multi-qubit equatorial state, and specifically deduce the final states and fidelities of the remote preparation of the three-qubit and four-qubit equatorial states under diverse types of noisy environments, namely, amplitude damping, bit flip, phase damping, phase flip, bit-phase flip, depolarization, and non-Markov environments. The results show that when the decoherence factors of the front six noises are equal, the influence degrees of phase damped noise, bit flip noise, phase flip noise, and bit-phase flip noise are similar, while the information loss caused by the amplitude damped noise and depolarizing noise is less. In particular, the bit flip noise and depolarizing noise may have more complex effects on the remote state preparation (RSP) schemes depending on the phase information of the target states, even for the ideal cases where the fidelity values are always 1 for specific phase relations. In the non-Markov environment, owing to the back and forth of information between the environment and systems, fidelities exhibit oscillating behavior and the minimum value may stay greater than zero for a long evolutionary time. These results are expected to have potential applications for understanding and avoiding the influence of noise on remote quantum communication and quantum networks.

Ville Bergholm, Mikko Möttönen, O.-P. Saira +3 more

Binayak Samadder Choudhury, Soumen Samanta

In the actual quantum communication process, there will inevitably be noise in the quantum channel. In this chapter, we consider teleportation protocols in noisy environment. There are different types of noises, which are amplitude-damping, bit-flip, phase-flip, phase-damping, depolarizing noise, etc. Throughout this chapter, four types of noises are considered, namely amplitude-damping, bit-flip, phase-flip, phase-damping, under which teleportation without and with control are presented. The analysis of fidelity of the process against the variation of noise parameters are also discussed. Teleportation through noisy environment have been discussed in a good number of papers like [ 43 , 57 , 60 , 63 , 69 , 79 , 92 , 96 , 114 , 178 , 198 , 204 ].

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Tomonori Tanizawa, Yuki Takeuchi, Shion Yamashika +2 more

Graph states are entangled states that are useful for several quantum information processing tasks, such as measurement-based quantum computation and quantum metrology. As the size of graph states realized in experiments increases, it becomes more essential to devise efficient methods for estimating the fidelity between the ideal graph state and an experimentally realized actual state. Any efficient fidelity-estimation method, in general, must use multiple experimental settings, i.e., needs to switch between at least two measurements. Recently, it has been shown that a single measurement is sufficient if the noise can be modeled as the phase-flip error. Since the bit-flip error should also occur in several experiments, it is desired to extend this simplest method to noise models that include phase and bit-flip errors. However, it seems to be nontrivial because their result strongly depends on properties of the phase-flip error. In this paper, by analyzing effects of the bit-flip error on stabilizer operators of graph states, we achieve the extension to the depolarizing noise, which is a major noise model including phase and bit-flip errors. We also numerically evaluate our simplest method for noise models interpolating between the phase-flip and depolarizing noises.

V. P. Belavkin, Simon Edwards