Strong-driving-assisted Unconventional Geometric Logic Gating In A Two-mode Cavity

Since the 1980s, scientists gradually realized that information theory, computer science and physics are correlated to each other in application. Moreover, physics principles plays fundamental role in unprecedented way in information theory. In classical sense of information, the information is encoded in simply two distinct states, usually called as a bit. However, quantum state can change continuously from these two states. It is therefore understandable that when the information is encoded into quantum states, the traditional framework of the information has a fundamental change. This is why a new discipline known as quantum information had been put forwarded and has been built up in order to deal with the information storage, transfer and calculation etc. with quantum states. Generally speaking, quantum information includes quantum communication and quantum computation. Quantum information has been greatly widened the horizon of science research, enriched and deepened our understanding of the microcosm, and also has demonstrated the remarkably potential application. In the realm of quantum information,cavity Quantum Electrodynamics (QED) is considered as one of the most effective scheme to realize, storage and transfer the quantum information. With the development of the science and technology, more and more quantum information techniques can be realized in experiment through the cavity QED scheme.This dissertation starts with introduction of four main experiment schemes in quantum information; and they are cavity-QED, ion trap, nuclear magnetic resonance and quantum dot. Since our work concentrates on the cavity-QED, so we introduce the basic theory of cavity-QED and the geometric phase in quantum information with its application in the cavity-QED. Then we present our research in detail on the strong-driving-assisted unconventional geometric logic gating in a two-mode cavity. The principal results obtained are summarized in the following three aspects: 1) We propose a candidate two-qubit unconventional geometric quantum gates on two identical three-level atoms in a two-mode cavity, strongly driven by a resonant classical field; 2) We have employed the double-Hamiltonian method to eliminate the cavity mode fluctuations due to the decay, so the fidelity in our approach is higher than in some other ones; 3) We built aπ-phase gate under the influence from the cavity decay. By numerical calculations with adopting the real values of physical parameters from microwave cavity experiments in different periodic situations, we studied the influence of the gating time, fidelity and success probability. Results show that our approach is advantageous for it has smaller gating time, higher fidelity and larger success probability.As the qubit-encoded levels are directly coupled by a laser or the cavity modes, our model involves less laser beams, which would reduce the experimental difficulty. Due to the small detuning, our gate could be carried out faster than others.