Fast implementation of four-dimensional entangled state in separately coupled cavities via shortcut to adiabatic passage

Abstract

Quantum information, as a comprehensive subject of quantum mechanics and information science, has a broad theoretical research value and application prospect. As a resource of quantum information, quantum entanglement has been studied thoroughly, which is not only significant to understand the features of quantum mechanics, but also of great value to the development of the method new quantum information processing. Therefore, the generation of entangled state is widely studied theoretically. In comparison to low-dimensional entangled states, multi-dimensional entangled states are not only safe but also efficient and error-tolerant for quantum computation. The adiabatic technique is one of the most widely used and proven techniques in quantum information science. The main advantages of this technique are that it is insensitive to the fluctuation of experimental parameters, and the interaction time of the system is not required to be controled accurately. However, limited by the adiabatic condition, it usually takes relatively long interaction time in scheme via adiabatic technique to achieve the target states. If the required evolution time is too long, the scheme may be useless. To overcome this problem, researchers have done a lot in the field of finding ways to shorten the long interaction time of adiabatic passage. Among these works, the technique named shortcuts to adiabatic passage is a successful work in this field and it has attracted a great deal of attention in recent years. In this paper, based on transitionless quantum driving to construct shortcuts to adiabatic passage, an efficient scheme to fast generate a four-dimensional entangled state of two-atom is proposed. The atoms are respectively trapped in the separate two-mode cavities which are connected by optical fiber. To achieve an alternative physically feasible system, the non-resonant dynamics is adopted to create a Hamiltonian which can exactly drive the system to evolve along the instantaneous eigenstates of the original Hamiltonian. As a result, if the system goes through adiabatic passage, it will evolve in the dark state, not transit to other states. Hence, using transitionless quantum driving to shortcuts to adiabatic passage, the evolutionary time in this scheme is much less than that in other schemes based on traditional adiabatic passage. The rigorous numerical simulations are conducted. The results show that with suitable pulsed laser parameters, this scheme is robust against decoherence arising from fiber decay, cavity decay and atomic spontaneous emission. Moreover, the scheme is more feasible in physics. That is, based on the proposed scheme, a high-fidelity four-dimensional entangled state of two-atom can be achieved.