01331nas a2200157 4500008004100000245004000041210003900081260001400120300001100134490000800145520091900153100002301072700002101095700002001116856003701136 2023 eng d00aSelf-dual quasiperiodic percolation0 aSelfdual quasiperiodic percolation c2/27/2023 a0241370 v1073 a

How does the percolation transition behave in the absence of quenched randomness? To address this question, we study two nonrandom self-dual quasiperiodic models of square-lattice bond percolation. In both models, the critical point has emergent discrete scale invariance, but none of the additional emergent conformal symmetry of critical random percolation. From the discrete sequences of critical clusters, we find fractal dimensions of Df=1.911943(1) and Df=1.707234(40) for the two models, significantly different from Df=91/48=1.89583... of random percolation. The critical exponents ν, determined through a numerical study of cluster sizes and wrapping probabilities on a torus, are also well below the ν=4/3 of random percolation. While these new models do not appear to belong to a universality class, they demonstrate how the removal of randomness can fundamentally change the critical behavior.

1 aSommers, Grace, M.1 aGullans, Michael1 aHuse, David, A. uhttps://arxiv.org/abs/2206.1129001741nas a2200181 4500008004100000245006600041210006300107260001300170520118700183100001801370700002301388700002401411700002101435700002001456700002501476700002101501856003701522 2023 eng d00aA sharp phase transition in linear cross-entropy benchmarking0 asharp phase transition in linear crossentropy benchmarking c5/8/20233 a

Demonstrations of quantum computational advantage and benchmarks of quantum processors via quantum random circuit sampling are based on evaluating the linear cross-entropy benchmark (XEB). A key question in the theory of XEB is whether it approximates the fidelity of the quantum state preparation. Previous works have shown that the XEB generically approximates the fidelity in a regime where the noise rate per qudit ε satisfies εN≪1 for a system of N qudits and that this approximation breaks down at large noise rates. Here, we show that the breakdown of XEB as a fidelity proxy occurs as a sharp phase transition at a critical value of εN that depends on the circuit architecture and properties of the two-qubit gates, including in particular their entangling power. We study the phase transition using a mapping of average two-copy quantities to statistical mechanics models in random quantum circuit architectures with full or one-dimensional connectivity. We explain the phase transition behavior in terms of spectral properties of the transfer matrix of the statistical mechanics model and identify two-qubit gate sets that exhibit the largest noise robustness.

1 aWare, Brayden1 aDeshpande, Abhinav1 aHangleiter, Dominik1 aNiroula, Pradeep1 aFefferman, Bill1 aGorshkov, Alexey, V.1 aGullans, Michael uhttps://arxiv.org/abs/2305.0495401834nas a2200157 4500008004100000245007600041210006900117260001400186520133100200100002901531700001601560700002501576700002101601700001701622856003701639 2021 eng d00aSingularities in nearly-uniform 1D condensates due to quantum diffusion0 aSingularities in nearlyuniform 1D condensates due to quantum dif c3/10/20213 a

Dissipative systems can often exhibit wavelength-dependent loss rates. One prominent example is Rydberg polaritons formed by electromagnetically-induced transparency, which have long been a leading candidate for studying the physics of interacting photons and also hold promise as a platform for quantum information. In this system, dissipation is in the form of quantum diffusion, i.e., proportional to k2 (k being the wavevector) and vanishing at long wavelengths as k→0. Here, we show that one-dimensional condensates subject to this type of loss are unstable to long-wavelength density fluctuations in an unusual manner: after a prolonged period in which the condensate appears to relax to a uniform state, local depleted regions quickly form and spread ballistically throughout the system. We connect this behavior to the leading-order equation for the nearly-uniform condensate -- a dispersive analogue to the Kardar-Parisi-Zhang (KPZ) equation -- which develops singularities in finite time. Furthermore, we show that the wavefronts of the depleted regions are described by purely dissipative solitons within a pair of hydrodynamic equations, with no counterpart in lossless condensates. We close by discussing conditions under which such singularities and the resulting solitons can be physically realized.

1 aBaldwin, Christopher, L.1 aBienias, P.1 aGorshkov, Alexey, V.1 aGullans, Michael1 aMaghrebi, M. uhttps://arxiv.org/abs/2103.0629301238nas a2200157 4500008004100000245005100041210005000092520077600142100001600918700002100934700002200955700001800977700002300995700002501018856003701043 2018 eng d00aSingle-photon bound states in atomic ensembles0 aSinglephoton bound states in atomic ensembles3 a

We illustrate the existence of single-excitation bound states for propagating photons interacting with N two-level atoms. These bound states can be calculated from an effective spin model, and their existence relies on dissipation in the system. The appearance of these bound states is in a one-to-one correspondence with zeros in the single-photon transmission and with divergent bunching in the second-order photon-photon correlation function. We also formulate a dissipative version of Levinson's theorem for this system by looking at the relation between the number of bound states and the winding number of the transmission phases. This theorem allows a direct experimental measurement of the number of bound states using the measured transmission phases.

1 aWang, Yidan1 aGullans, Michael1 aBrowaeys, Antoine1 aPorto, J., V.1 aChang, Darrick, E.1 aGorshkov, Alexey, V. uhttps://arxiv.org/abs/1809.0114701372nas a2200181 4500008004100000245007800041210006900119260001500188300001100203490000800214520084100222100002101063700001601084700001701100700001801117700001901135856003601154 2016 eng d00aSisyphus Thermalization of Photons in a Cavity-Coupled Double Quantum Dot0 aSisyphus Thermalization of Photons in a CavityCoupled Double Qua c2016/07/25 a0568010 v1173 a

A strongly driven quantum system, coupled to a thermalizing bath, generically evolves into a highly non-thermal state as the external drive competes with the equilibrating force of the bath. We demonstrate a notable exception to this picture for a microwave resonator interacting with a periodically driven double quantum dot (DQD). In the limit of strong driving and long times, we show that the resonator field can be driven into a thermal state with a chemical potential given by a harmonic of the drive frequency. Such tunable chemical potentials are achievable with current devices and would have broad utility for quantum simulation in circuit quantum electrodynamics. As an example, we show how several DQDs embedded in an array of microwave resonators can induce a phase transition to a Bose-Einstein condensate of light.

1 aGullans, Michael1 aStehlik, J.1 aLiu, Y., -Y.1 aPetta, J., R.1 aTaylor, J., M. uhttp://arxiv.org/abs/1512.0124801150nas a2200193 4500008004100000245004800041210004800089260001500137300001400152490000800166520063700174100001700811700001600828700001600844700002100860700001900881700001800900856003800918 2015 eng d00aSemiconductor double quantum dot micromaser0 aSemiconductor double quantum dot micromaser c2015/01/15 a285 - 2870 v3473 a The coherent generation of light, from masers to lasers, relies upon the specific structure of the individual emitters that lead to gain. Devices operating as lasers in the few-emitter limit provide opportunities for understanding quantum coherent phenomena, from THz sources to quantum communication. Here we demonstrate a maser that is driven by single electron tunneling events. Semiconductor double quantum dots (DQDs) serve as a gain medium and are placed inside of a high quality factor microwave cavity. We verify maser action by comparing the statistics of the emitted microwave field above and below the maser threshold. 1 aLiu, Y., -Y.1 aStehlik, J.1 aEichler, C.1 aGullans, Michael1 aTaylor, J., M.1 aPetta, J., R. uhttp://arxiv.org/abs/1507.06359v101278nas a2200205 4500008004100000245009000041210006900131260001400200490000700214520065300221100001600874700001300890700002000903700002700923700002100950700001800971700002500989700002101014856003701035 2014 eng d00aScattering resonances and bound states for strongly interacting Rydberg polaritons 0 aScattering resonances and bound states for strongly interacting  c2014/11/30 v903 a We provide a theoretical framework describing slow-light polaritons interacting via atomic Rydberg states. We use a diagrammatic method to analytically derive the scattering properties of two polaritons. We identify parameter regimes where polariton-polariton interactions are repulsive. Furthermore, in the regime of attractive interactions, we identify multiple two-polariton bound states, calculate their dispersion, and study the resulting scattering resonances. Finally, the two-particle scattering properties allow us to derive the effective low-energy many-body Hamiltonian. This theoretical platform is applicable to ongoing experiments. 1 aBienias, P.1 aChoi, S.1 aFirstenberg, O.1 aMaghrebi, Mohammad, F.1 aGullans, Michael1 aLukin, M., D.1 aGorshkov, Alexey, V.1 aBüchler, H., P. uhttp://arxiv.org/abs/1402.7333v101034nas a2200169 4500008004100000245005800041210005700099260001500156490000800171520053900179100002100718700001800739700002300757700002900780700001800809856003700827 2013 eng d00aSingle-photon nonlinear optics with graphene plasmons0 aSinglephoton nonlinear optics with graphene plasmons c2013/12/110 v1113 a We show that it is possible to realize significant nonlinear optical interactions at the few photon level in graphene nanostructures. Our approach takes advantage of the electric field enhancement associated with the strong confinement of graphene plasmons and the large intrinsic nonlinearity of graphene. Such a system could provide a powerful platform for quantum nonlinear optical control of light. As an example, we consider an integrated optical device that exploits this large nonlinearity to realize a single photon switch. 1 aGullans, Michael1 aChang, D., E.1 aKoppens, F., H. L.1 ade Abajo, F., J. García1 aLukin, M., D. uhttp://arxiv.org/abs/1309.2651v3