Single-shot readout in graphene quantum dots

Abstract

Electrostatically defined quantum dots in bilayer graphene offer a promising platform for spin qubits with presumably long coherence times due to low spin-orbit coupling and low nuclear spin density. We demonstrate two different experimental approaches to measure the decay times of excited states. The first is based on direct current measurements through the quantum device. Pulse sequences are applied to control the occupation of ground and excited states. We observe a lower bound for the excited state decay on the order of hundred microseconds. The second approach employs a capacitively coupled charge sensor to study the time dynamics of the excited state using the Elzerman technique. We find that the relaxation time of the excited state is of the order of milliseconds. We perform single-shot readout of our two-level system with a visibility of $87.1\%$, which is an important step for developing a quantum information processor in graphene.

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Cited by in corpus (26)

• Long-lived valley states in bilayer graphene quantum dots
• Spin-orbit proximity in MoS${}_2$/bilayer graphene heterostructures
• Spin-Valley Protected Kramers Pair in Bilayer Graphene
• Counting Statistics of Single Electron Transport in Bilayer Graphene Quantum Dots
• Coherent Charge Oscillations in a Bilayer Graphene Double Quantum Dot
• Spin-valley locked excited states spectroscopy in a one-particle bilayer graphene quantum dot
• Collective excitations in chiral Stoner magnets
• Extended Hubbard model describing small multi-dot arrays in bilayer graphene
• Pauli blockade catalogue and three- and four-particle Kondo effect in bilayer graphene quantum dots
• Shot noise in resonant tunneling: Role of inelastic scattering
• Switching spin filling sequence in a bilayer graphene quantum dot through trigonal warping
• Dipole coupling of a bilayer graphene quantum dot to a high-impedance microwave resonator
• Electric-field independent spin-orbit coupling gap in hBN-encapsulated bilayer graphene
• Tunable p-n junction barriers in few-electron bilayer graphene quantum dots
• Electrically-tunable graphene nanomechanical resonators
• Three-carrier spin blockade and coupling in bilayer graphene double quantum dots
• Tunable spin-orbit splitting in bilayer graphene/WSe${}_2$ quantum devices
• Phonon-limited valley life times in single-particle bilayer graphene quantum dots
• Tuning confined states and valley g-factors by quantum dot design in bilayer graphene
• Ultra-Fast All-Electrical Universal Nano-Qubits
• Increasing the proximity induced spin-orbit coupling in bilayer graphene/WSe${}_2$ heterostructures with pressure
• Radio-frequency charge detection on graphene electron-hole double quantum dots
• Graphene-based quantum heterospin graphs
• Quantum-Hall Spectroscopy of Elliptically Deformed Graphene Nanobubble Qubits
• Unprecedented Spin-Lifetime of Itinerant Electrons in Natural Graphite Crystals
• Disentangling orbital and confinement contributions to $g$-factor in Ge/SiGe hole quantum dots