Microwave spectroscopy of a carbon nanotube charge qubit

Abstract

Carbon nanotube quantum dots allow accurate control of electron charge, spin and valley degrees of freedom in a material which is atomically perfect and can be grown isotopically pure. These properties underlie the unique potential of carbon nanotubes for quantum information processing, but developing nanotube charge, spin, or spin-valley qubits requires efficient readout techniques as well as understanding and extending quantum coherence in these devices. Here, we report on microwave spectroscopy of a carbon nanotube charge qubit in which quantum information is encoded in the spatial position of an electron. We combine radio-frequency reflectometry measurements of the quantum capacitance of the device with microwave manipulation to drive transitions between the qubit states. This approach simplifies charge-state readout and allows us to operate the device at an optimal point where the qubit is first-order insensitive to charge noise. From these measurements, we are able to quantify the degree of charge noise experienced by the qubit and obtain an inhomogeneous charge coherence of 5 ns. We use a chopped microwave signal whose duty-cycle period is varied to measure the decay of the qubit states, yielding a charge relaxation time of 48 ns.

References in corpus (10)

• Coupling of Spin and Orbital Motion of Electrons in Carbon Nanotubes
• Microwave-driven coherent operations of a semiconductor quantum dot charge qubit
• Spin-orbit interaction and anomalous spin relaxation in carbon nanotube quantum dots
• Hyperfine interaction and electron-spin decoherence in graphene and carbon nanotube quantum dots
• Landau-Zener-Stuckelberg Interferometry of a Single Electron Charge Qubit
• Molecular states in carbon nanotube double quantum dots
• Mesoscopic admittance of a double quantum dot
• Clean carbon nanotubes coupled to superconducting impedance-matching circuits
• Spin relaxation in quantum dots due to electron exchange with leads
• Carbon nanotube quantum dots on hexagonal boron nitride

Cited by in corpus (7)

• Nonadiabatic Landau-Zener-Stückelberg-Majorana transitions, dynamics, and interference
• Review of performance metrics of spin qubits in gated semiconducting nanostructures
• Low-temperature environments for quantum computation and quantum simulation
• Real-time milli-Kelvin thermometry in a semiconductor qubit architecture
• Josephson junctions based on ultraclean carbon nanotubes
• Parametric longitudinal coupling of a semiconductor charge qubit and a RF resonator
• Microwave spectroscopy of spin-orbit coupled states: energy detuning versus interdot coupling modulation