Approaching the ultrastrong coupling regime between an Andreev level and a microwave resonator

Abstract

Josephson junctions formed in semiconductor nanowires host Andreev bound states and serve as a physical platform to realize Andreev qubits tuned by electrostatic gating. With the Andreev bound state being confined to the nanoscale weak link, it couples to a circuit-QED architecture via the state-dependent supercurrent flowing through the weak link. Thus, increasing this coupling strength is a crucial challenge for this architecture. Here, we demonstrate the fabrication and microwave characterization of a weak link which is defined in an InAs-Al (core-half shell) nanowire and embedded in a superconducting loop with a lumped-element resonator patterned from a thin NbTiN film with high kinetic inductance. We investigated several devices with various weak link lengths and performed spectroscopy that revealed pair transitions and single-quasiparticle transitions arising from spin-orbit split Andreev bound states. Our approach offers a compact geometry and a large resonator impedance above 12 k$\Omega$ at a resonator frequency of 8 GHz, which facilitates large coupling in the system. For the pair transitions, the experimentally observed energy level splitting demonstrates the coupling to an Andreev level of 490 MHz. We apply a perturbative model that shows good agreement with the experimental data and extract the maximum coupling of 968~MHz. Moreover, we show that the coupling is even stronger to an Andreev level with a higher transmission. In addition, spectroscopy of single-quasiparticle transitions reveals spin-orbit split Andreev bound states with the extracted spin-photon coupling of 77 MHz.

References in corpus (35)

• Circuit Quantum Electrodynamics: Coherent Coupling of a Single Photon to a Cooper Pair Box
• Circuit Quantum Electrodynamics
• Ultrastrong coupling between light and matter
• Beyond the Jaynes-Cummings model: circuit QED in the ultrastrong coupling regime
• Ultrastrong coupling regimes of light-matter interaction
• Epitaxy of Semiconductor-Superconductor nanowires
• Quantum Coherence in a One-Electron Semiconductor Charge Qubit
• Strong Coupling of a Single Electron in Silicon to a Microwave Photon
• Efficient and robust analysis of complex scattering data under noise in microwave resonators
• Tunable superconducting nanoinductors
• Coherent manipulation of Andreev states in superconducting atomic contacts
• Strong Coupling Cavity QED with Gate-Defined Double Quantum Dots Enabled by a High Impedance Resonator
• Coherent manipulation of an Andreev spin qubit
• Andreev Level Qubit
• Spin-orbit splitting of Andreev states revealed by microwave spectroscopy
• Direct microwave measurement of Andreev-bound-state dynamics in a proximitized semiconducting nanowire
• Andreev quantum dots for spin manipulation
• Direct manipulation of a superconducting spin qubit strongly coupled to a transmon qubit
• Quantum amplification and simulation of strong and ultrastrong coupling of light and matter
• Superconducting Spin Qubits
• Continuous monitoring of a trapped, superconducting spin
• Andreev spin qubits in multichannel Rashba nanowires
• Low-loss tunable metamaterials using superconducting circuits with Josephson junctions
• Charge transport in InAs nanowire Josephson junctions
• Signatures of interactions in the Andreev spectrum of nanowire Josephson junctions
• Circuit-QED with phase-biased Josephson weak links
• Spectroscopy of spin-split Andreev levels in a quantum dot with superconducting leads
• Controlled dephasing of Andreev states in superconducting quantum point-contacts
• Strong coupling between a microwave photon and a singlet-triplet qubit
• Microwave spectroscopy of interacting Andreev spins
• Microwave spectroscopy of Andreev states in InAs nanowire-based hybrid junctions using a flip-chip layout
• Blueprint for all-to-all connected superconducting spin qubits
• Current-Phase Relation and Josephson Inductance of Superconducting Cooper Pair Transistor
• Ground state phase diagram and "parity flipping'' microwave transitions in a gate-tunable Josephson Junction
• Andreev spin relaxation time in a shadow-evaporated InAs weak link

Cited by in corpus (3)

• Finite Length Effects and Coulomb Interaction in Ge Quantum Well-Based Josephson Junctions Probed with Microwave Spectroscopy
• Effects of electron-electron interaction and spin-orbit coupling on Andreev pair qubits in quantum dot Josephson junctions
• Slave-spin approach to the Anderson-Josephson quantum dot