Gatemon Qubit on a Germanium Quantum-Well Heterostructure

Area of Science:

• Quantum Computing
• Condensed Matter Physics
• Superconducting Circuits

Background:

• Gatemons are superconducting qubits that utilize a gate-tunable semiconducting weak link.
• Existing superconducting qubits often rely on Josephson junctions, but gate-tunability offers enhanced control.
• Germanium-based heterostructures are emerging as promising platforms for quantum devices.

Purpose of the Study:

• To engineer and characterize a gatemon qubit device utilizing a Ge/SiGe heterostructure.
• To investigate the superconducting proximity effect in a Ge quantum well for qubit applications.
• To demonstrate gate-voltage tunability of qubit properties and assess coherence times.

Main Methods:

• Fabrication of a gatemon device with an aluminum microwave circuit on a Ge/SiGe heterostructure.
• Utilizing the two-dimensional hole gas in the Ge quantum well as a gate-tunable weak link.
• Performing Rabi oscillation and Ramsey interference measurements to probe qubit dynamics.

Main Results:

• Demonstrated a gate-tunable qubit frequency over a 3.5 GHz range.
• Achieved relaxation times (T1) up to 119 ns and Ramsey coherence times (T2*) up to 70 ns.
• Reproduces results from similar Ge/SiGe heterostructure platforms, confirming device viability.

Conclusions:

• The Ge/SiGe heterostructure platform successfully hosts a functional gatemon qubit.
• This work validates a novel approach for creating gate-tunable superconducting weak links.
• The platform shows potential for developing gatemons and parity-protected cos(2ϕ) qubits.