1306.6732 (Hefeng Wang)

A quantum algorithm for obtaining the energy spectrum of a physical
system using a resonating probe qubit    [PDF]

Hefeng Wang

We present a quantum algorithm for obtaining the energy spectrum of a physical system. A qubit is coupled to a $n$-qubit quantum register that represents the system to form a register $R$. We prepare $R$ in a general reference state and construct a general operator that excites $R$ from the reference state to the state space of the system. A probe qubit is coupled to $R$ such that the probe exhibits a dynamical response only when it resonates with a transition between the reference state and the energy eigenstates of the system. By varying the probe's frequency, the energy spectrum and the eigenstates of the system can be obtained. In this algorithm, no initial guess on the eigenstate of the system is required.

View original: http://arxiv.org/abs/1306.6732