| Quantum state operations are significant research topic in quantum physics. Presently, a lot of works focus on realization of.quantum state, both theoretically and experimentally, such as Bell state, GHZ state, cluster state, etc. These quantum states are important. In one hand, they can be used to testify some phenomenon of physics. For example, Bell state can be utilized to testify Bell inequality, proving the nonlocal correlation characteristic of quantum mechanics. In the other hand, preparation of quantum states is the first step to realize quantum computation. Cluster states with high entanglement are prerequisite for one way computation. In fact, quantum computing can be regarded as the process of controlling quantum states and their evolution. Therefore, to prepare quantum states effectively becomes the primary issue that researchers of quantum computation should consider.Up to now, quantum states operations are based on the famous Rabi oscillation model. Via controlling the pulse duration accurately, the desired quantum state can be prepared. However, for the demanding requirement of experimental operation, errors in the course of experiments can’t be avoided, inducing the states which we don’t need. For that reason, we try to seek an approach theoretically to realize a pulse-insensitive controlling. In our proposal, an additional Stark chirped pulse is needed, which chirps the energy levels. By relatively controlling the Stark pulse and pumping pulse, we can achieve an adiabatic passage, resulting perfect single-qubit operations. Besides, we can also construct two-qubit logic gates with this method. With the help of the above two kinds of operations, scalable quantum computing can be achieved. To demonstrate the feasibility of our proposal, we simulate the quantum logic operations with experiment parameters in superconducting quantum circuits. The result means that our proposal can be achived in principle.An expected advantage of our proposal is the insensitivity to environment. In experiments, the energy levels are considered to be stable. By the driving of which the frequency is as the same as energy levels gap, the transition of population is supposed to be achieved. But in the process of realistic experiments, quantum systems definitely suffer from environmental interference and the energy levels are shifted slightly. Our proposal chirps the energy levels actively, which can suppress the influence of environment and be immune to noise of environment. Another feature of our proposal is no matter what states the system occupies, ground state or excited state, the population reversion of two levels of a quantum bit can be done. |
