# Dr Eran Ginossar

### Biography

Eran Ginossar is a Senior Lecturer at the Department of Physics and Advanced Technology Institute at the University of Surrey. He received his PhD in 2008 from the Weizmann Institute of Science in Israel on researching Quantum optical effects in semiconductors. He moved to Yale University to study the physics of superconducting circuits, a field that is rapidly progressing in creating viable devices for quantum information processing at the intersection between quantum optics and solid state. Additional topics of interest include interaction effects in mesoscopic systems, quantum optics and quantum simulations. Eran has joined the university of Surrey in 2011. He is a member of the IoP, APS and held an EPSRC fellowship until Sept. 2014.

### Areas of specialism

### University roles and responsibilities

- MPhys Research Year Placements Coordinator

### News

### Research

### Research interests

(for PhD projects please see email me and see below)

*Circuit Quantum Electrodynamics, Quantum optics and Quantum information processing:* Measurement theory and control of Qubits and Resonators. These projects are geared towards developing the building blocks and protocols for quantum information processing with solid state devices. My research in this field is strongly motivated by experiments which routinely raise research questions in quantum optics and coherent control. The methodology involves taking a non-equilibrium open system approach to modeling and employing large scale computer simulations.

*Mesoscopic physics and topological states: *Electronic interferometers in the quantum Hall state, persistent currents in normal metal rings, Majorana fermions.

Areas of research proposed for a PhD project -

- Topological states of matter in superconducting circuits
- Phase transitions in driven-dissipative systems
- Optimal control of superconducting quantum processors
- Mesoscopic physics of topological insulators and superconductors
- Quantum dynamics and control of hybrid devices

### My teaching

Essential Mathematics (PHY1034)

Advanced Quantum Physics (PHY3044)

Quantum magnetism and superconductivity (PHYM062)

### Courses I teach on

## Undergraduate

### My publications

### Publications

quantum electrodynamics, New Journal of Physics 18 pp. 023028-023028

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.

circuit quantum electrodynamics, In: Fluctuating Nonlinear Oscillators. From nanomechanics to quantum superconducting circuits 8 Oxford University Press

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).

Statistics of Coulomb Blockade Peak Spacings,

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.

electrodynamics,

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.

Luminescence, Physical Review B (Condensed Matter and Materials Physics) 72 (7) 075333 American Physical Society

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.

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.

oscillator, Physical Review A 97 033828 American Physical Society

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.

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.

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.

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.