Polariton-polariton coherent coupling in a molecular spin-superconductor chip
Year: 2026
Type: article
Abstract: The ability to establish coherent communication channels is key for scaling up quantum devices. Here, we engineer interactions between distant polaritons, hybrid spin-photon excitations formed at different lumped-element superconducting resonators within a chip. The chip consists of several resonator pairs, slightly detuned in frequency to make them addressable, capacitively coupled within each pair and inductively coupled to a common readout line. They interact locally with samples of PTMr and Tripak$^{-}$ organic free radicals, deposited onto their inductors, which provide model $S = 1/2$, $g \simeq 2$ spin ensembles. Frequency-dependent microwave transmission experiments, performed at very low temperatures, measure polariton frequencies as a function of magnetic field in different scenarios. When only one resonator within a pair hosts a molecular sample, the results evidence that spins couple remotely to the empty LER as well as to the local cavity mode. If both resonators interact with a spin ensemble, the magnetic field tunes the polariton frequencies relative to each other, on account of the different spin-photon interactions at each LER. When polaritons are brought into mutual resonance, an avoided level crossing emerges that gives direct spectroscopic evidence for a coherent polariton-polariton interaction mediated by the circuit. Pump-probe experiments reveal that the excitation of a polariton within a connected pair is felt, thus it can be read out, by the other one. These observations, backed by model calculations, illustrate the control and detection of distant photon-photon and spin-spin correlations and entanglement in a scalable modular chip.
Source: PRX Quantum
DOI: 10.1103/xvjl-h44h
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,450
Awards: G1204740081, G1622782223, G1658930240, G1799927510, G234454427, G2799588417, G2825053243, G2906055632, G3020948319, G318412399, G3845300180, G3945525359, G4088250386, G410571670, G4137806753, G4358239568, G451917667, G4617935805, G4993905653, G5195188938, G546199279, G5539308778, G5606506422, G5967599077, G6218905885, G631184005, G6520718613, G6619481953, G7069624064, G7069849, G7704543894, G8294824355, G848677485, G8888022036, G929308097, G983705713
OpenAlex ID: W7215931951