Laser manipulation of quantum wave packets with attoseconds phase control -encoding of molecular wave packets-

摘要

The temporal coherent control of molecular wave packets using a pair of time-separated femtosecond (fs) laser pulses is theoretically studied for the isolated HgAr molecule in the gas phase. A short laser pulse (time duration: 300fs, center wavelength: 254.37nm) induces the vibronic (A ~30~+, v)←(X ~10~+, v=0) transition of the HgAr molecule and generates a wave packet (WP) of the periodic nuclear motion constrained within the A state potential well. The WP is a superposition of the low-lying vibrational eigenstates (mainly, v=3 and 4). Two WPs, generated by a pair of the laser pulses, interact constructively or destructively to form a variety of spatial wave modes depending on the delay time between the laser pulses. These variations of the wave modes arise from that the relative populations at the individual vibration levels changes with the delay time change. By projecting the A state WP onto each of the eigenstates, it is found that the relative amplitudes of the v=3 and v=4 eigenstates oscillate with the phase difference π each other. This suggests a new method of quantum encoding or rotational quantum operation by means of the double-pulse-phase control technique.