Microsecond-lived quantum states in a carbon-based circuit driven by cavity photons.

Area of Science:

• Quantum Computing
• Condensed Matter Physics
• Nanotechnology

Background:

• Semiconductor quantum dots are promising for quantum processors.
• Integrating quantum dots into microwave cavities enables long-range coupling.
• Cavity integration typically reduces quantum dot coherence.

Purpose of the Study:

• To investigate coherence times of carbon nanotube double quantum dots in a microwave cavity.
• To explore quantum state manipulation using cavity photons.
• To assess carbon as a host material for spin qubits in circuit quantum electrodynamics.

Main Methods:

• Fabrication of a suspended carbon nanotube double quantum dot with ferromagnetic contacts.
• Embedding the quantum dot within a microwave cavity.
• Performing quantum state manipulations using microwave cavity photons.

Main Results:

• Demonstrated coherence times of approximately 1.3 μs.
• Achieved coherence times two orders of magnitude greater than previous carbon quantum circuits.
• Exceeded coherence times of silicon-based quantum dots in similar environments by one order of magnitude.

Conclusions:

• Carbon nanotube quantum dots in microwave cavities show significantly enhanced coherence.
• This work demonstrates the potential of carbon as a viable host material for spin qubits.
• The findings pave the way for scalable carbon-based quantum processors utilizing circuit quantum electrodynamics.