Quantum Fluids of Light

We bridge condensed matter physics with photonics using exciton-polaritons: particles that condense and form quantum many-body states.

We have one fully funded (covering tuition fees and living expenses) PhD position for this academic year in Giant Rydberg polaritons.

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Projects

Giant Rydberg polaritons

Giant Rydberg polaritons

Polaritonic Devices

High speed spintronics using room-temperature polariton condensates

Spin Lattices

Interacting spin lattices of exciton-polariton condensates

Team

Dr Hamid Ohadi

Principal Investigator

Scott Stevenson

Research Assistant

Felix Scott

Summer Project Student

Teaching

Hamid is teaching two courses for 2018-2019 academic year:

  • PH5005: Laser Physics 2
  • PH5181: Photonics Lab

More information coming soon.

Publication Highlights

Synchronization Crossover of Polariton Condensates in Weakly Disordered Lattices

We demonstrate that the synchronization of a lattice of solid-state condensates when intersite tunneling is switched on depends strongly on the weak local disorder. This finding is vital for implementation of condensate arrays as computation devices. The condensates here are nonlinear bosonic fluids of exciton-polaritons trapped in a weakly disordered Bose-Hubbard potential, where the nearest-neighboring tunneling rate (Josephson coupling) can be dynamically tuned. The system can thus be tuned from a localized to a delocalized fluid as the number density or the Josephson coupling between nearest neighbors increases. The localized fluid is observed as a lattice of unsynchronized condensates emitting at different energies set by the disorder potential. In the delocalized phase, the condensates synchronize and long-range order appears, evidenced by narrowing of momentum and energy distributions, new diffraction peaks in momentum space, and spatial coherence between condensates. Our paper identifies similarities and differences of this nonequilibrium crossover to the traditional Bose-glass to superfluid transition in atomic condensates.
Physical Review B (2018)

Spin Order and Phase Transitions in Chains of Polariton Condensates

We demonstrate that multiply coupled spinor polariton condensates can be optically tuned through a sequence of spin-ordered phases by changing the coupling strength between nearest neighbors. For closed four-condensate chains these phases span from ferromagnetic (FM) to antiferromagnetic (AFM), separated by an unexpected crossover phase. This crossover phase is composed of alternating FM-AFM bonds. For larger eight-condensate chains, we show the critical role of spatial inhomogeneities and demonstrate a scheme to overcome them and prepare any desired spin state. Our observations thus demonstrate a fully controllable nonequilibrium spin lattice.
Physical Review Letters (2017)

Recent Publications

More Publications

Electrical Tuning of Nonlinearities in Exciton-Polariton Condensates. Physical Review Letters (2018)

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Stochastic spin flips in polariton condensates: nonlinear tuning from GHz to sub-Hz. New Journal of Physics (2018)

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Synchronization Crossover of Polariton Condensates in Weakly Disordered Lattices. Physical Review B (2018)

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Strain-assisted optomechanical coupling of polariton condensate spin to a micromechanical resonator. Applied Physics Letters (2017)

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Driven-dissipative spin chain model based on exciton-polariton condensates. Physical Review B (2017)

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Recent & Upcoming Talks

EPIC 2018 (invited)
Dec 5, 2018

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