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Efficient multiple-quantum transition processes in an n-qubit spin system

Xijia Miao
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Abstract

The whole Hilbert state space of an n-qubit spin system can be divided into (n+1) state subspaces according to the angular momentum theory of quantum mechanics. Here it is shown that any unknown state in such a state subspace, whose dimensional size is proportional to either a polynomial or exponential function of the qubit number n, can be transferred efficiently into a larger subspace with a dimensional size generally proportional to an exponential function of the qubit number by the multiple-quantum unitary transformation with a subspace-selective multiple-quantum unitary operator. The efficient quantum circuits for the subspace-selective multiple-quantum unitary operators are really constructed.

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Xijia Miao. 2004-11-07. Efficient multiple-quantum transition processes in an n-qubit spin system. https://arxiv.org/abs/quant-ph/0411046

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