Spectral signature of high-order photon processes enhanced by Cooper-pair pairing
arXiv:2312.15075 · doi:10.1038/s41467-025-62047-8
Abstract
Inducing interactions between individual photons is key for photonic quantum information and studying many-body photon states. Superconducting circuits are well suited to combine strong interactions with low losses. Typically, microwave photons are stored in an oscillator shunted by a Josephson junction, where the zero-point phase fluctuations across the junction determine the strength and order of photon interactions. Most superconducting nonlinear oscillators operate with small phase fluctuations, where two-photon Kerr interactions dominate. In our experiment, we shunt a high-impedance oscillator with a dipole element favoring the tunneling of paired Cooper pairs. This leads to large phase fluctuations of 3.4, accessing a regime where transition frequencies shift non-monotonically with excitation number. From spectroscopy, we extract two-, three-, and four-photon interaction energies, all of similar strength and exceeding the photon loss rate. Our results open a new regime of high-order photon interactions in microwave quantum optics.
arXiv comment16 pages, 14 figures
References in corpus (21)
- Circuit Quantum Electrodynamics: Coherent Coupling of a Single Photon to a Cooper Pair Box
- Fluxonium: single Cooper pair circuit free of charge offsets
- Quantum phase transitions of light
- Observation of quantum state collapse and revival due to the single-photon Kerr effect
- New material platform for superconducting transmon qubits with coherence times exceeding 0.3 milliseconds
- A Dissipatively Stabilized Mott Insulator of Photons
- Granular aluminum: A superconducting material for high impedance quantum circuits
- Pairing of Cooper Pairs in a Fully Frustrated Josephson Junction Chain
- Probing Correlations, Indistinguishability and Entanglement in Microwave Two-Photon Interference
- Observation of three-photon bound states in a quantum nonlinear medium
- Possible realization of an ideal quantum computer in Josephson junction array
- Superconducting circuit protected by two-Cooper-pair tunneling
- The superconducting quasicharge qubit
- Protected Josephson Rhombi Chains
- Quantization of inductively-shunted superconducting circuits
- Degeneracy-preserving quantum non-demolition measurement of parity-type observables for cat-qubits
- Quantum vortices of strongly interacting photons
- Geometric superinductance qubits: Controlling phase delocalization across a single Josephson junction
- Nonlinear Optics Quantum Computing with Circuit-QED
- Collective modes in the fluxonium qubit
- Phase-slip oscillator: few-photon non-linearities