Dephasing of a qubit due to quantum and classical noise

Y. Akbari-Kourbolagh, Sh. Razavian

Y. M. Galperin, B. L. Altshuler, D. V. Shantsev

Daniel Crow, Robert Joynt

Dephasing decoherence induced by interaction of one qubit with a quantum bath can be simulated classically by random unitary evolution without the need for a bath and this random unitary evolution is equivalent to the quantum case. For a general dephasing model and a single-qubit system, we explicitly construct the noise functional and completely specify the random unitary evolution. To demonstrate the technique, we applied our results to three paradigmatic models: spin-boson, central spin, and quantum impurity. For multiple qubits, we identify a class of generalized quantum dephasing models that can be simulated classically. Finally we show that depolarizing quantum models can be simulated classically for all dimensionalities of the principal system.

Y. M. Galperin, B. L. Altshuler, Daniil V. Shantsev

Pakhshan Espoukeh, Robabeh Rahimi, S. Salimi +1 more

Many-qubit entanglement is crucial for quantum information processing although its exploitation is hindered by the detrimental effects of the environment surrounding the many-qubit system. It is thus of importance to study the dynamics of general multipartite non-classical correlation, including but not restricted to entanglement, under noise. We did this study for four-qubit Greenberger–Horne–Zeilinga (GHZ) state under most common noises in an experiment and found that non-classical correlation is more robust than entanglement except when it is imposed to dephasing channel. Quantum discord presents a sudden transition in its dynamics for Pauli-X and Pauli-Y noises as well as Bell-diagonal states interacting with dephasing reservoirs and it decays monotonically for Pauli-Z and isotropic noises.

Masashi Ban, Sachiko Kitajima, Fumiaki Shibata