研究目的
Investigating charge-tunneling processes between a quantum dot and a superconducting island through gate sensing to understand spin-dependent quasiparticle tunneling and Cooper pair tunneling, and to guide future dispersive parity measurements of Majorana modes.
研究成果
The study successfully demonstrated direct detection of charge tunneling between a quantum dot and a superconducting island using radio-frequency gate sensing. It revealed spin-dependent quasiparticle tunneling and Cooper pair tunneling, depending on the energy scales of the system. The method allows for RF-only spectroscopy of superconducting subgap states without transport, providing a valuable tool for future studies of Majorana modes and topological qubits.
研究不足
The study is limited by the specific energy scales of the devices used, which affect the accessibility of quasiparticle states and the types of tunneling processes observed. The method's sensitivity to tunneling amplitudes and the need for precise control over gate voltages may also limit its applicability.
1：Experimental Design and Method Selection:
The experiment involves forming a hybrid double dot in an InAs nanowire with an epitaxially grown Al shell, using gate-tunable subgap states in the superconducting island. Tunneling barriers are implemented with gates to control tunneling rates.
2：Sample Selection and Data Sources:
Two nominally-identical devices, labeled A and B, were measured. The QD plunger was connected to an off-chip, superconducting resonator to probe charge tunneling.
3：List of Experimental Equipment and Materials:
InAs nanowire with Al shell, gates insulated by 10 nm AlOx, off-chip superconducting resonator.
4：Experimental Procedures and Operational Workflow:
Measurements were done at temperatures of T ≈ 20 mK and at zero magnetic field. The resonator response near the resonance frequency was used to probe charge tunneling on and off the dot.
5：Data Analysis Methods:
The resonator response was analyzed to detect charge tunneling processes, with numerical simulations supporting the observations.
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