Abstract
Entanglement can exist not only in the microscopic system (e.g., atom, photon, and ion trap) but also in macroscopic systems. According to recent research, entanglement can be achieved and controlled in superconducting devices. The quantum dynamics and entanglement mechanism of the coupled superconducting phase qubit and a two-level system (TLS) were demonstrated when the bipartite system was under microwave driving. Besides, the results reveal that when the system was experiencing decoherence, entanglement (concurrence) of the coupled superconducting phase qubit and TLS would oscillate damply with microwave driving time, even exhibiting concurrence sudden death and revival. The coupling effect of the superconducting qubit and TLS system and the resonant microwave together help to achieve entanglement, while concurrence death and concurrence revival are dependent on the decoherence source and mechanism, for example, the resonant microwave driving time acting on the bipartite coupling system. Furthermore, the simulation results show the entanglement of the coupled qubit and TLS system also depends on the purity of the initial states of the system. The article carried out a numerical simulation on the entanglement of different initial states, and the results showed that the entanglement of the coupled system changes with different initial states. For different initial states, entanglement, sudden death, and rejuvenation are still visible.
Highlights
Entanglement is considered as a vital resource to achieve quantum computing and quantum computer [1,2,3,4,5]
With more microwave driving time, the concurrence between the superconducting qubit and two-level system (TLS) decreases more rapidly or disappear completely. us, concurrence death and revival are dependent on the resonant microwave driving time that acts on the bipartite qubit-TLS system
In order to find out the entanglement mechanism of the superconducting quantum system, we confirm that the preparation of the initial state of the system has an important influence on the entanglement of the superconducting quantum system. e simulation results have shown that the entanglement of the coupled qubit and TLS system depends on the purity of the initial states of the system
Summary
Entanglement is considered as a vital resource to achieve quantum computing and quantum computer [1,2,3,4,5]. Entanglement decay induced by the environment is considered as an important research project for quantum information and quantum cryptography [23,24,25,26,27]. It leaves two fundamental questions unanswered: first, what is the generation mechanism of entanglement between the superconducting qubit and the TLS; second, how the environment affects entanglement of the system, thereby leading to concurrence death or concurrence revival. Entanglement (concurrence) of the coupled system was simulated, suggesting that concurrence oscillates damply with microwave driving time and shows concurrence death and revival phenomena. When the system is prepared in an entangled state, the entanglement differs when the system is initially set in a separated state, which is helpful to the experimental preparation and measurement of quantum entanglement
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