Dynamical charge susceptibility in nonequilibrium double quantum dots

Abstract

Double quantum dots are one of the promising two-state quantum systems for realizing qubits. In the quest of successfully manipulating and reading information in qubit systems, it is of prime interest to control the charge response of the system to a gate voltage, as filled in by the dynamical charge susceptibility. We theoretically study this quantity for a nonequilibrium double quantum dot by using the functional integral approach and derive its general analytical expression. One highlights the existence of two lines of maxima as a function of the dot level energies, each of them being split under the action of a bias voltage. In the low frequency limit, we derive the capacitance and the charge relaxation resistance of the equivalent quantum RC-circuit with a notable difference in the range of variation for $R$ depending on whether the system is connected in series or in parallel. By incorporating an additional triplet state in order to describe the situation of a double quantum dot with spin, we obtain results for the resonator phase response which are in qualitative agreement with recent experimental observations in spin qubit systems. These results show the wealth of information brought by the knowledge of dynamical charge susceptibility in double quantum dots with potential applications for spin qubits.

6 pages, 6 figures, SM

References in corpus (10)

• Circuit Quantum Electrodynamics with a Spin Qubit
• Rapid high-fidelity gate-based spin read-out in silicon
• Mesoscopic Charge Relaxation
• A Coherent RC Circuit
• Mesoscopic admittance of a double quantum dot
• Unified description of correlations in double quantum dots
• A Radio Frequency Charge Parity Meter
• Renormalization group study of capacitively coupled double quantum dots
• Fermi liquid approach to the quantum RC circuit: renormalization-group analysis of the Anderson and Coulomb blockade models
• Kondo effect in a one-electron double quantum dot: Oscillations of the Kondo current in a weak magnetic field

Cited by in corpus (1)

• Beyond-adiabatic Quantum Admittance of a Semiconductor Quantum Dot at High Frequencies: Rethinking Reflectometry as Polaron Dynamics