Eran Ginossar

Dr Eran Ginossar

+44 (0)1483 682714
20 ATI 02

Academic and research departments

Advanced Technology Institute, Department of Physics.


Areas of specialism

Mesoscopic physics; Quantum optics and quantum non-equilibrium; Superconducting circuits ; Quantum optimal control; Topological states of matter; Quantum simulation and quantum computing

University roles and responsibilities

  • MPhys Research Year Placements Coordinator


    Research interests

    My teaching

    Courses I teach on


    My publications


    Bleszynski-Jayich AC, Shanks WE, Peaudecerf B, Ginossar E, von Oppen F, Glazman L, Harris JGE (2009) Persistent Currents in Normal Metal Rings, SCIENCE326(5950)pp. 272-275 AMER ASSOC ADVANCEMENT SCIENCE
    Ginossar E, Bishop LS, Schuster DI, Girvin SM (2010) Protocol for high-fidelity readout in the photon-blockade regime of circuit QED,PHYSICAL REVIEW A82(2)ARTN 022335 AMER PHYSICAL SOC
    Kirchmair G, Vlastakis B, Leghtas Z, Nigg SE, Paik H, Ginossar E, Mirrahimi M, Frupzio L, Girvin SM, Schoelkopf RJ (2012) Observation of quantum state collapse and revival due to the single-photon Kerr effect,NATURE495(7440)pp. 205-209 NATURE PUBLISHING GROUP
    Joo J, Elliott M, Oi DKL, Ginossar E, Spiller TP (2016) Deterministic amplification of Schroedinger cat states in circuit quantum electrodynamics,New Journal of Physics18pp. 023028-023028
    We propose a dynamical scheme for deterministically amplifying photonic Schroedinger cat states based on a set of optimal state-transfers. The scheme can be implemented in strongly coupled qubit-cavity systems and is well suited to the capabilities of state of the art superconducting circuits. The ideal analytical scheme is compared with a full simulation of the open Jaynes-Cummings model with realistic device parameters. This amplification tool can be utilized for practical quantum information processing in non-classical continuous-variable states.
    Schuster DI, Sears AP, Ginossar E, DiCarlo L, Frunzio L, Morton JJL, Wu H, Briggs GAD, Buckley BB, Awschalom DD, Schoelkopf RJ (2010) High-Cooperativity Coupling of Electron-Spin Ensembles to Superconducting Cavities,PHYSICAL REVIEW LETTERS105(14)ARTN 140501 AMER PHYSICAL SOC
    Ginossar E, Bishop LS, Girvin SM (2012) Nonlinear oscillators and high fidelity qubit state measurement in circuit quantum electrodynamics, In: Fluctuating Nonlinear Oscillators. From nanomechanics to quantum superconducting circuits8 Oxford University Press
    In this book chapter we analyze the high excitation nonlinear response of the Jaynes-Cummings model in quantum optics when the qubit and cavity are strongly coupled. We focus on the parameter ranges appropriate for transmon qubits in the circuit quantum electrodynamics architecture, where the system behaves essentially as a nonlinear quantum oscillator and we analyze the quantum and semi-classical dynamics. One of the central motivations is that under strong excitation tones, the nonlinear response can lead to qubit quantum state discrimination and we present initial results for the cases when the qubit and cavity are on resonance or far off-resonance (dispersive).
    Bishop LS, Ginossar E, Girvin SM (2010) Response of the Strongly Driven Jaynes-Cummings Oscillator,PHYSICAL REVIEW LETTERS105(10)ARTN 100505 AMER PHYSICAL SOC
    Bishop LS, Tornberg L, Price D, Ginossar E, Nunnenkamp A, Houck AA, Gambetta JM, Koch J, Johansson G, Girvin SM, Schoelkopf RJ (2009) Proposal for generating and detecting multi-qubit GHZ states in circuit QED,NEW JOURNAL OF PHYSICS11ARTN 073040 IOP PUBLISHING LTD
    We present a complete classification of the electron-electron interaction in chaotic quantum dots based on expansion in inverse powers of $1/M$, the number of the electron states in the Thouless window, $M \simeq k_F R$. This classification is quite universal and extends and enlarges the universal non interacting RMT statistical ensembles. We show that existing Coulomb blockade peak spacing data for $B=0$ and $B\ne 0$ is described quite accurately by the interacting GSE and by its extension to $B\ne 0$. The bimodal structure existing in the interacting GUE case is completely washed out by the combined effect of the spin orbit, pairing and higher order residual interactions.
    Ginossar E, Glazman LI, Ojanen T, von Oppen F, Shanks WE, Bleszynski-Jayich AC, Harris JGE (2010) Mesoscopic persistent currents in a strong magnetic field,PHYSICAL REVIEW B81(15)ARTN 155448 AMER PHYSICAL SOC
    We propose a deterministic scheme for teleporting an unknown qubit through continuous-variable entangled states in superconducting circuits. The qubit is a superconducting two-level system and the bipartite quantum channel is a photonic entangled coherent state between two cavities. A Bell-type measurement performed on the hybrid state of solid and photonic states brings a discrete-variable unknown electronic state to a continuous-variable photonic cat state in a cavity mode. This scheme further enables applications for quantum information processing in the same architecture of circuit-QED such as verification and error-detection schemes for entangled coherent states. Finally, a dynamical method of a self-Kerr tunability in a cavity state has been investigated for minimizing self-Kerr distortion and all essential ingredients are shown to be experimentally feasible with the state of the art superconducting circuits.
    Ginossar E, Levit S (2005) Semiconductor Microstructure in a Squeezed Vacuum: Electron-Hole Plasma Luminescence,Physical Review B (Condensed Matter and Materials Physics)72(7)075333 American Physical Society
    We consider a semiconductor quantum-well placed in a wave guide microcavity and interacting with the broadband squeezed vacuum radiation, which fills one mode of the wave guide with a large average occupation. The wave guide modifies the optical density of states so that the quantum well interacts mostly with the squeezed vacuum. The vacuum is squeezed around the externally controlled central frequency $\om_0$, which is tuned above the electron-hole gap $E_g$, and induces fluctuations in the interband polarization of the quantum-well. The power spectrum of scattered light exhibits a peak around $\om_0$, which is moreover non-Lorentzian and is a result of both the squeezing and the particle-hole continuum. The squeezing spectrum is qualitatively different from the atomic case. We discuss the possibility to observe the above phenomena in the presence of additional non-radiative (e-e, phonon) dephasing.
    Johnson BR, Reed MD, Houck AA, Schuster DI, Bishop LS, Ginossar E, Gambetta JM, DiCarlo L, Frunzio L, Girvin SM, Schoelkopf RJ (2010) Quantum non-demolition detection of single microwave photons in a circuit,NATURE PHYSICS6(9)pp. 663-667 NATURE PUBLISHING GROUP
    Elliott M, Ginossar E (2016) Applications of the Fokker-Planck equation in circuit quantum electrodynamics, Physical Review A: Atomic, Molecular and Optical Physics94(4)
    We study exact solutions of the steady state behaviour of several non-linear open quantum systems which can be applied to the eld of circuit quantum electrodynamics. Using Fokker-Planck equations in the generalised P-representation we investigate the analytical solutions of two fundamental models. First, we solve for the steady-state response of a linear cavity that is coupled to an approximate transmon qubit and use this solution to study both the weak and strong driving regimes, using analytical expressions for the moments of both cavity and transmon elds, along with the Husimi Q-function for the transmon. Second, we revisit exact solutions of quantum Du ng oscillator which is driven both coherently and parametrically while also experiencing decoherence by the loss of single and pairs of photons. We use this solution to discuss both stabilisation of Schrodinger cat states and the generation of squeezed states in parametric ampli ers, in addition to studying the Q-functions of the di erent phases of the quantum system. The eld of superconducting circuits, with its strong nonlinearities and couplings, has provided access to new parameter regimes in which returning to these exact quantum optics methods can provide valuable insights.
    Neder I, Ginossar E (2008) Behavior of electronic interferometers in the nonlinear regime,PHYSICAL REVIEW LETTERS100(19)ARTN 196806 AMER PHYSICAL SOC
    Ginossar E, Levinson Y, Levit S (2008) Coherent optical control of correlation waves of spins in semiconductors,PHYSICAL REVIEW B78(20)ARTN 205204 AMER PHYSICAL SOC
    Murch KW, Weber SJ, Beck KM, Ginossar E, Siddiqi I (2013) Reduction of the radiative decay of atomic coherence in squeezed vacuum,NATURE499(7456)pp. 62-65 NATURE PUBLISHING GROUP
    Murch KW, Ginossar E, Weber SJ, Vijay R, Girvin SM, Siddiqi I (2012) Quantum state sensitivity of an autoresonant superconducting circuit,PHYSICAL REVIEW B86(22)ARTN 220503 AMER PHYSICAL SOC
    Elliott M, Ginossar E (2015) Enhancement and state tomography of a squeezed vacuum with circuit quantum electrodynamics, PHYSICAL REVIEW A92(1)ARTN 013826 AMER PHYSICAL SOC
    Rabinak I, Ginossar E, Levit S (2007) Atom in a coherently controlled squeezed vacuum,PHYSICAL REVIEW A76(1)ARTN 013821 AMER PHYSICAL SOC
    Elliott MJ, Ginossar E (2015) Enhancement and state tomography of a squeezed vacuum with circuit quantum electrodynamics,Physical Review A: Atomic, Molecular and Optical Physics92013826 American Physical Society
    We study the dynamics of a general quartic interaction Hamiltonian under the influence of dissipation and nonclassical driving. We show that this scenario could be realized with a cascaded superconducting cavity-qubit system in the strong dispersive regime in a setup similar to recent experiments. In the presence of dissipation, we find that an effective Hartree-type decoupling with a Fokker-Planck equation yields a good approximation. We find that the stationary state is approximately a squeezed vacuum, which is enhanced by the Q factor of the cavity but conserved by the interaction. The qubit nonlinearity, therefore, does not significantly influence the highly squeezed intracavity microwave field but, for a range of realistic parameters, enables characterization of itinerant squeezed fields.
    Mavrogordatos T, Tancredi G, Elliott MJ, Peterer M, Patterson A, Rahamim J, Leek P, Ginossar E, Szymanska M (2017) Simultaneous bistability of qubit and resonator in circuit quantum electrodynamics,Physical Review Letters118040402 American Physical Society
    We explore the joint activated dynamics exhibited by two quantum degrees of freedom: a cavity mode oscillator which is strongly coupled to a superconducting qubit in the strongly coherently driven dispersive regime. Dynamical simulations and complementary measurements show a range of parameters where both the cavity and the qubit exhibit sudden simultaneous switching between two metastable states. This manifests in ensemble averaged amplitudes of both the cavity and qubit exhibiting a partial coherent cancellation. Transmission measurements of driven microwave cavities coupled to transmon qubits show detailed features which agree with the theory in the regime of simultaneous switching
    Mavrogordatos T, Szafulski P, Ginossar E, Szymanska M (2016) Mean-field and quantum-fluctuation dynamics in the driven dispersive Jaynes-Cummings model,SPIE Proceedings10142
    In this work we investigate the regime of amplitude bistability in the driven dissipative Jaynes-Cummings (JC) model. We study the semiclassical equation dynamics in contrast to entangled cavity-photon and qubit quantum trajectories, discussing our results in the context of an out-of-equilibrium first order quantum dissipative phase transition for a single JC resonator. Finally, we compare the switching process between metastable states for the two system degrees of freedom by examining a single realization of the random qubit vector in the Bloch sphere next to the intracavity amplitude quasi distributions at given time instants.
    Allen J, Kosut R, Joo J, Leek P, Ginossar E (2017) Optimal control of two qubits via a single cavity drive in circuit quantum electrodynamics,Physical Review A: Atomic, Molecular and Optical Physics95(4)042325 American Physical Society
    Optimization of the fidelity of control operations is of critical importance in the pursuit of fault tolerant quantum computation. We apply optimal control techniques to demonstrate that a single drive via the cavity in circuit quantum electrodynamics can implement a high fidelity two-qubit all-microwave gate that directly entangles the qubits via the mutual qubit-cavity couplings. This is performed by driving at one of the qubits? frequencies which generates a conditional two-qubit gate, but will also generate other spurious interactions. These optimal control techniques are used to find pulse shapes that can perform this two-qubit gate with high fidelity, robust against errors in the system parameters. The simulations were all performed using experimentally relevant parameters and constraints.
    Ginossar E, Grosfeld E (2014) Microwave transitions as a signature of coherent parity mixing effects in the Majorana-transmon qubit,NATURE COMMUNICATIONS54772 NATURE PUBLISHING GROUP
    Solid-state Majorana fermions are generating intensive interest because of their unique properties and possible applications in fault tolerant quantum memory devices. Here we propose a method to detect signatures of Majorana fermions in hybrid devices by employing the sensitive apparatus of the superconducting charge-qubit architecture and its efficient coupling to microwave photons. In the charge and transmon regimes of this device, we find robust signatures of the underlying Majorana fermions that are, remarkably, not washed out by the smallness of the Majorana contribution to the Josephson current. It is predicted that at special gate bias points the photon-qubit coupling can be switched off via quantum interference, and in other points it is exponentially dependent on the control parameter EJ/EC. We propose that this device could be used to manipulate the quantum state of the Majorana fermion and realize a tunable high coherence four-level system in the superconducting-circuit architecture.
    Ginossar Eran, Joo J (2016) Efficient scheme for hybrid teleportation via entangled coherent states in circuit quantum electrodynamics,Scientific Reports6 Nature Publishing Group
    We propose a deterministic scheme for teleporting an unknown qubit state through continuous-variable entangled states in superconducting circuits. The qubit is a superconducting two-level system and the bipartite quantum channel is a microwave photonic entangled coherent state between two cavities. A Bell-type measurement performed on the hybrid state of solid and photonic states transfers a discrete-variable unknown electronic state to a continuous-variable photonic cat state in a cavity mode. In order to facilitate the implementation of such complex protocols we propose a design for reducing the self-Kerr nonlinearity in the cavity. The teleporation scheme enables quantum information processing operations with circuit-QED based on entangled coherent states. These include state veri?cation and single-qubit operations with entangled coherent states. These are shown to be experimentally feasible with the state of the art superconducting circuits.
    Superconducting circuits provide an architecture upon which cavity quantum electrodynamics (QED) can be implemented at microwave frequencies in a highly tunable environment. Known as circuit QED, these systems can achieve larger nonlinearities, stronger coupling and greater controllability than can be achieved in cavity QED, all in a customisable, solid state device, making this technology an exciting test bed for both quantum optics and quantum information processing. These new parameter regimes open up new avenues for quantum technology, while also allowing older quantum optics results to finally be tested. In particular is is now possible to experimentally produce nonclassical states, such as squeezed and Schr\"odinger cat states, relatively simply in these devices. Using open quantum systems methods, in this thesis we investigate four problems which involve the use of nonclassical states in circuit QED. First we investigate the effects of a Kerr nonlinearity on the ability to preserve transported squeezed states in a superconducting cavity, and whether this setup permits us to generate, and perform tomography, of a highly squeezed field using a qubit, with possible applications in the characterisation of sources of squeezed microwaves. Second, we present a novel scheme for the amplification of cat states using a coupled qubit and external microwave drives, inspired by the stimulated Raman adiabatic passage. This scheme differs from similar techniques in circuit QED in that it is deterministic and therefore compatible with a protocol for stabilising cat states without the need for complex dissipation engineering. Next we use solutions of Fokker-Planck equations to study the exact steady-state response of two nonlinear systems: a transmon qubit coupled to a readout resonator, where we find good agreement with experiments and see simultaneous bistability of the cavity and transmon; and a parametrically driven nonlinear resonator, where we compare the classical and quantum phases of the system and discuss applications in the generation of squeezed states and stabilisation of cat states. Finally, we investigate the use of two different types of superconducting qubits in a single experiment, seeing that this enables engineering of the self- and cross-Kerr effects in a line of cavities. This could provide a valuable means of entangling cavity states, in addition to a resource for quantum simulation.
    Le Nguyen H., Fisher Andrew J., Ginossar Eran (2017) Extended Hubbard model for mesoscopic transport in donor arrays in silicon,Physical Review B96(24)245406pp. 245406-1 American Physical Society
    Arrays of dopants in silicon are promising platforms for the quantum simulation of the Fermi-Hubbard model. We show that the simplest model with only on-site interaction is insufficient to describe the physics of an array of phosphorous donors in silicon due to the strong intersite interaction in the system. We also study the resonant tunneling transport in the array at low temperature as a mean of probing the features of the Hubbard physics, such as the Hubbard bands and the Mott gap. Two mechanisms of localization which suppresses transport in the array are investigated: The first arises from the electron-ion core attraction and is significant at low filling; the second is due to the sharp oscillation in the tunnel coupling caused by the intervalley interference of the donor electron's wave function. This disorder in the tunnel coupling leads to a steep exponential decay of conductance with channel length in one-dimensional arrays, but its effect is less prominent in two-dimensional ones. Hence, it is possible to observe resonant tunneling transport in a relatively large array in two dimensions.
    Elliott Matthew, Joo Jaewoo, Ginossar Eran (2018) Designing Kerr interactions using multiple superconducting qubit types in a single circuit,New Journal of Physics20(2)023037 IOP Publishing
    The engineering of Kerr interactions is of great interest for processing quantum information in multipartite quantum systems and for investigating many-body physics in a complex cavity-qubit network. We study how coupling multiple different types of superconducting qubits to the same cavity modes can be used to modify the self- and cross-Kerr effects acting on the cavities and demonstrate that this type of architecture could be of significant benefit for quantum technologies. Using both analytical perturbation theory results and numerical simulations, we first show that coupling two superconducting qubits with opposite anharmonicities to a single cavity enables the effective self-Kerr interaction to be diminished, while retaining the number splitting effect that enables control and measurement of the cavity field. We demonstrate that this reduction of the self-Kerr effect can maintain the fidelity of coherent states and generalised Schrödinger cat states for much longer than typical coherence times in realistic devices. Next, we find that the cross-Kerr interaction between two cavities can be modified by coupling them both to the same pair of qubit devices. When one of the qubits is tunable in frequency, the strength of entangling interactions between the cavities can be varied on demand, forming the basis for logic operations on the two modes. Finally, we discuss the feasibility of producing an array of cavities and qubits where intermediary and on-site qubits can tune the strength of self- and cross-Kerr interactions across the whole system. This architecture could provide a way to engineer interesting many-body Hamiltonians and be a useful platform for quantum simulation in circuit quantum electrodynamics.
    Mavrogordatos Th, Barratt F, Asari U, Szafulski P, Ginossar Eran, Szymanska M (2018) Rare quantum metastable states in the strongly dispersive Jaynes-Cummings oscillator,Physical Review A97033828 American Physical Society
    We present evidence of metastable rare quantum- uctuation switching for the driven dissipative Jaynes-Cummings (JC) oscillator coupled to a zero-temperature bath in the strongly dispersive regime. We show that single-atom complex amplitude bistability is accompanied by the appearance of a low-amplitude long-lived transient state, hereinafter called `dark state', having a distribution with quasi-Poissonian statistics both for the coupled qubit and cavity mode. We find that the dark state is linked to a spontaneous ipping of the qubit state, detuning the cavity to a low-photon response. The appearance of the dark state is correlated with the participation of the two metastable states in the dispersive bistability, as evidenced by the solution of the Master Equation and single quantum trajectories.
    Elliott Matthew, Joo Jaewoo, Ginossar Eran Kerr engineering in circuit quantum electrodynamics, University of Surrey
    Matmon G, Ginossar E, Villis B, Kolker A, Lim T, Solanki H, Schofield S, Curson N, Li J, Murdin B, Fisher A, Aeppli G (2018) 2D-3D crossover in a dense electron liquid in silicon,Physical Review B97155306 American Physical Society
    Doping of silicon via phosphine exposures alternating with molecular beam epitaxy overgrowth is a path to Si:P substrates for conventional microelectronics and quantum information technologies. The technique also provides a new and well-controlled material for systematic studies of two-dimensional lattices with a half-filled band. We show here that for a dense (ns = 2.8 × 1014 cm?2 ) disordered two-dimensional array of P atoms, the full field angle-dependent magnetostransport is remarkably well described by classic weak localization theory with no corrections due to interaction effects. The two- to three-dimensional cross-over seen upon warming can also be interpreted using scaling concepts, developed for anistropic three-dimensional materials, which work remarkably except when the applied fields are nearly parallel to the conducting planes.
    Joo Jaewoo, Elliott Matthew, Oi Daniel K, Ginossar Eran, Spiller Timothy P Supporting Data for 'Deterministic amplification of Schrödinger cat states in circuit quantum electrodynamics', University of Surrrey
    Mavrogordatos Th. K., Tancredi G, Elliott M, Peterer MJ, Patterson A, Rahamim J, Leek PJ, Ginossar E, Szymanska MH Data for the paper "Simultaneous bistability of qubit and resonator in circuit quantum electrodynamics", University of Surrey
    Superconducting circuits are one of the leading architectures in quantum computing. To undertake quantum computing one must be able to perform quantum gates; however, two-qubit gates are still limited in fidelity and gate time. The cross-resonance gate is a two-qubit gate that uses direct microwave drives and has seen much success in its implementation; but, there are theoretical indications that it has not yet reached the coherence limited fidelity value and its gate time is still relatively long compared with other quantum gate methods. Quantum optimal control theory is a powerful tool in the design of controls for quantum operations and has shown the capability to improve gate fidelities and reduce gate times. Robust quantum optimal control methodologies have further built on this to develop high fidelity quantum gates that are robust to uncertainties and noise in the system. In this thesis we use robust quantum optimal control theory to achieve these goals for the cross-resonance gate in a variety of superconducting qubit architectures. First, we investigate two superconducting qubits embedded in a common 3D microwave cavity in which the control drive is implemented via the common cavity mode of the cavity. We determine pulse shapes that implement the cross-resonance gate that are robust to uncertainty in the qubit transition frequencies for both a strictly two-level superconducting qubit and a three-level qubit. Second, we look at the cross-resonance gate with direct drives on each qubit, finding the minimal time to perform the cross-resonance gate with pulses that are robust to uncertainty in a measured system parameter for three cases: two three-level qubits with no drive crosstalk, two three-level qubits with some drive crosstalk, and two two-level qubits. Lastly, we report on simulations undertaken towards implementing a robust, high fidelity cross-resonance gate in a novel superconducting quantum device known as the coaxmon.
    Le Nguyen, Fisher Andrew J., Curson Neil J., Ginossar Eran (2019) Topological phases of a dimerized Fermi-Hubbard model for semiconductor nano-lattices,npj Quantum Information Nature Research (Springer Nature)
    Motivated by recent advances in fabricating artificial lattices in semiconductors and their promise for quantum simulation of topological materials, we study the one-dimensional dimerized Fermi- Hubbard model. We show how the topological phases at half-filling can be characterized by a reduced Zak phase defined based on the reduced density matrix of each spin subsystem. Signatures of bulk-boundary correspondence are observed in the triplon excitation of the bulk and the edge states of uncoupled spins at the boundaries. At quarter-filling we show that owing to the presence of the Hubbard interaction the system can undergo a transition to the topological ground state of the non-interacting Su-Schrieffer-Heeger model with the application of a moderate-strength external magnetic field. We propose a robust experimental realization with a chain of dopant atoms in silicon or gate-defined quantum dots in GaAs where the transition can be probed by measuring the tunneling current through the many-body state of the chain.
    Yavilberg Konstantin, Ginossar Eran, Grosfield Eytan (2019) Differentiating Majorana from Andreev bound states in a superconducting circuit,Physical Review B100241408 American Physical Society
    We investigate the low-energy theory of a one-dimensional finite capacitance topological Josephson junction. Charge fluctuations across the junction couple to resonant microwave fields and can be used to probe microscopic excitations such as Majorana and Andreev bound states. This marriage between localized microscopic degrees of freedom and macroscopic dynamics of the superconducting phase, leads to unique spectroscopic patterns which allow us to reveal the presence of Majorana fermions among the low-lying excitations.