Abstract
The hybrid system of electron spins and resonator photons is an attractive architecture for quantum computing owing to the long coherence times of spins and the promise of long-distance coupling between arbitrary pairs of qubits via photons. For the device to serve as a building block for a quantum processer, it is also necessary to readout the spin qubit state. Here we analyze in detail the measurement process of an electron spin singlet-triplet qubit in quantum dots using a coupled superconducting resonator. We show that the states of the spin singlet-triplet qubit lead to readily observable features in the spectrum of a microwave field through the resonator. These features provide useful information on the hybrid system. Moreover, we discuss the working points which can be implemented with high performance in the current state-of-the-art devices. These results can be used to construct the high fidelity measurement toolbox in the spin-circuit QED system.
Highlights
The ability to couple and manipulate qubit with the help of well-controlled electromagnetic fields has played an important role in the field of cavity quantum electrodynamics (CQED)[1,2,3]
Readout of single-electron spin qubit state with the superconducting resonator signal, which is a first step toward the goal of using the resonator to realize the high performance measurement
CQED architectures have been proposed and implemented to couple various electron spin qubits in quantum dots with a superconducting resonator[30,33,34,35,36,37,38,39,40,41,42,43]. These initial demonstrations motivate our research for probing the spin qubit using resonator photons that bring the generality and flexibility of CQED to the electron spin setting
Summary
Hamiltonian of the hybrid system with electron spin in quantum dot and photon in resonator. The electron spin states can have particular charge character through the spin-charge hybrid method This gives rise to a large effective spin-photon coupling strength of MHz. Recently, CQED architectures have been proposed and implemented to couple various electron spin qubits in quantum dots with a superconducting resonator[30,33,34,35,36,37,38,39,40,41,42,43]. In the realistic situation[30,44], we include the third level: the singlet state with two electrons in the right dot (0, 2)S This quantum dot system can be described by a Hamiltonian for (1, 1)T0 , (1, 1)S and (0, 2)S : HQD = Δ00B. The ωr k CRZR and the correspondinteraction between the quantum dot and the resonator voltageVof the resonator
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