Numerical Analysis of Optimized Coherent Control Pulses.pdfVIP

Numerical Analysis of Optimized Coherent Control Pulses P. Karbach,1 S. Pasini,1 and G. S. Uhrig1 1Lehrstuhl f¨ur Theoretische Physik I, Technische Universit¨at Dortmund, Otto-Hahn Straße 4, 44221 Dortmund, Germany (Dated: August 26, 2008) Numerically we simulate the effect of optimized coherent control pulses with a finite duration on a qubit in a bath of spins. The pulses of finite duration are compared with ideal instantaneous pulses. In particular, we show that properly designed short pulses can approximate ideal instantaneous pulses up to a certain order in the shortness of the pulse. We provide examples of such pulses, quantify the discrepancy from the ideal case and compare their effect for various ranges of the 8 coupling constants. 0 0 PACS numbers: 03.67.Lx, 03.67.Pp, 75.40.Mg, 76.60.-k 2 g I. INTRODUCTION on the basis of semiconductor technology so far only the u A spin echo technique has been implemented [16, 17, 18]. But computations for quantum dot systems show that The coherent control of quantum systems continues to 6 be a topic of great interest. The possibility of maintain- more elaborate pulse sequences are very likely to be use- 2