Magyar Tudományos Akadémia WIGNER FIZIKAI KUTATÓKÖZPONT
SZILÁRDTESTFIZIKAI ÉS OPTIKAI INTÉZET
1121 Budapest, Konkoly-Thege út 29-33, tel. 392-2212

 

SZFI kollokvium

 

Tóth Géza

University of the Basque Country UPV/EHU, vendéglátó: Kiss Tamás

Efficient algorithm for multi-qudit twirling for ensemble quantum computation

 

We present an efficient algorithm for twirling a multiqudit quantum state. The algorithm can be used for approximating the twirling operation in an ensemble of physical systems in which the systems cannot be individually accessed. It can also be used for computing the twirled density matrix on a classical computer. The method is based on a simple nonunitary operation involving a random unitary. When applying this basic building block iteratively, the mean squared error of the approximation decays exponentially. In contrast, when averaging over random unitary matrices the error decreases only algebraically. We present evidence that the unitaries in our algorithm can come from a very imperfect random source or can even be chosen deterministically from a set of cyclically alternating matrices. Based on these ideas we present a quantum circuit realizing twirling efficiently

[1] G. Tóth and J.J. García-Ripoll, Efficient algorithm for multi-qudit twirling for ensemble quantum computation, Phys. Rev. A 75, 042311 (2007); quant-ph/0609052.
http://optics.szfki.kfki.hu/~toth/Publications/PRA07_twirl.pdf

 

2013. július 25, csütörtök, 10:00:00

I. épület, Tanácsterem

 

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