In this Letter, we present a physical scheme for implementing the discrete quantum Fourier transform in a coupled semiconductor double quantum dot system. The main controlled-R gate operation can be decomposed into many simple and feasible unitary tr
ansformations. The current scheme would be a useful step towards the realization of complex quantum algorithms in the quantum dot system.
Universal set of quantum gates are realized from the conduction-band electron spin qubits of quantum dots embedded in a microcavity via two-channel Raman interaction. All of the gate operations are independent of the cavity mode states, emph{i.e.}, i
nsensitive to the thermal cavity field. Individual addressing and effective switch of the cavity mediated interaction are directly possible here. Meanwhile, gate operations also can be carried out in parallel. The simple realization of needed interaction for selective qubits makes current scenario more suitable for scalable quantum computation.
We present a physical scheme for implementing quantum phase estimation via weakly coupled double quantum-dot molecules embedded in a microcavity. During the same process of implementation, we can also realize the calibration of a timepiece based on t
he estimated phase. We use the electron-hole pair states in coupled double quantum-dot molecules to encode quantum information, where the requirement that two quantum dots are exactly identical is not necessary. Our idea can also be generalized to other systems, such as atomic, trapped ion and linear optics system.
