Superconducting atomic contacts inductively coupled to a microwave resonator

Area of Science:

• Condensed Matter Physics
• Quantum Computing
• Superconductivity

Background:

• Superconducting atomic contacts exhibit unique quantum phenomena, such as Andreev levels.
• Understanding and controlling these Andreev levels is crucial for advancing quantum technologies.
• Existing methods for probing these levels have limitations in terms of precision and control.

Purpose of the Study:

• To describe and characterize a novel microwave setup for probing Andreev levels.
• To demonstrate the spectroscopic analysis of transitions between Andreev levels.
• To provide insights into the coherent manipulation of these quantum states.

Main Methods:

• Utilizing a superconducting loop with an atomic contact, inductively coupled to a coplanar resonator.
• Monitoring the resonator's reflection coefficient near its resonance frequency.
• Performing spectroscopy by varying the magnetic flux through the loop and a second microwave tone frequency.

Main Results:

• Successfully characterized the microwave setup's performance.
• Observed and spectrally resolved the transitions between two Andreev levels.
• Demonstrated the potential for coherent manipulation of these quantum states.

Conclusions:

• The developed microwave setup is effective for probing Andreev levels in superconducting atomic contacts.
• The spectroscopic technique allows for detailed characterization of Andreev level transitions.
• This work paves the way for controlled quantum operations on superconducting atomic contacts.