The operations of quantum logic gates with pure and mixed initial states

Abstract

The implementations of quantum logic gates realized by the rovibrational states of a C(12)O(16) molecule in the X((1)Σ(+)) electronic ground state are investigated. Optimal laser fields are obtained by using the modified multitarget optimal theory (MTOCT) which combines the maxima of the cost functional and the fidelity for state and quantum process. The projection operator technique together with modified MTOCT is used to get optimal laser fields. If initial states of the quantum gate are pure states, states at target time approach well to ideal target states. However, if the initial states are mixed states, the target states do not approach well to ideal ones. The process fidelity is introduced to investigate the reliability of the quantum gate operation driven by the optimal laser field. We found that the quantum gates operate reliably whether the initial states are pure or mixed.

Low-bias negative differential resistance in junction of a benzene between zigzag-edged phosphorene nanoribbons

“…Various interesting physical properties have been observed or predicted in molecular junctions including cur rent switching [5][6][7][8], rectification [9,10], spin filtering [11,12], negative differ ential resistance (NDR) [13][14][15], and so on. This promises that the molecular junctions have broad potential application in many fields, such as the logic operation [16], data storage [17], and thermoelectric materials [18,19].…”

Effect of laser pulse shaping parameters on the fidelity of quantum logic gates

“…The majority of theoretical studies within diatomic quantum computing, using shaped laser pulses, produce excellent qubit control but with laser pulses that are difficult, or perhaps impossible, to realize experimentally and/or only show proof of principle applications on a particular choice of diatomic molecule. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] In contrast, we previously studied the performance of shaped laser pulses on a general model diatomic 31 and the ability to achieve high control with laser pulses having very few parameters (binary pulse shaping). 32 The theoretical optimizing or shaping of laser pulses generally comes in two forms: optimal control theory (OCT) 33,34 and genetic algorithm (GA) 11 optimization.…”