Proposal for Detection of the 0^{'} and π^{'} Phases in Quantum-Dot Josephson Junctions.

The competition between the Kondo correlation and superconductivity in quantum-dot Josephson junctions (QDJJs) has been known to drive a quantum phase transition between 0 and π junctions. Theoretical studies so far have predicted that under strong Coulomb correlations the 0-π transition should go through intermediate states, 0^{'} and π^{'} phases. By combining a nonperturbative numerical method and the resistively shunted junction model, we investigated the magnetic-field-driven phase transition of the QDJJs in the Kondo regime and found that the low-field magnetotransport exhibits a unique feature which can be used to distinguish the intermediate phases.

Topology detection in cavity QED.

We explore the physics of topological lattice models immersed in c-QED architectures for arbitrary coupling strength with the photon field. We propose the use of the cavity transmission as a topological marker and study its behaviour. For this, we develop an approach combining the input-output formalism with a Mean-Field plus fluctuations description of the setup.

Photovoltage oscillations in encapsulated graphene.

We theoretically analyze the rise of photovoltage oscillations in hexagonal boron-nitride (h-BN) encapsulated monolayer graphene (h-BN/graphene/h-BN) when irradiated with terahertz radiation. We use an extension of the radiation-driven electron orbit model, successfully applied to study the oscillations obtained in irradiated magnetotransport of GaAs/AlGaAs heterostructures. The extension takes mainly into account that now the carriers are massive Dirac fermions.

Simulation of 1D Topological Phases in Driven Quantum Dot Arrays.

We propose a driving protocol which allows us to use quantum dot arrays as quantum simulators for 1D topological phases. We show that by driving the system out of equilibrium, one can imprint bond order in the lattice (producing structures such as dimers, trimers, etc.) and selectively modify the hopping amplitudes at will.

Discontinuities in Driven Spin-Boson Systems due to Coherent Destruction of Tunneling: Breakdown of the Floquet-Gibbs Distribution.

If an open quantum system is periodically driven with high frequency and the driving commutes with the system-bath coupling operator, it is known that the system approaches a Floquet-Gibbs state, a generalization of Gibbs states to periodically driven systems. Here, we investigate the stationary state of an ac-driven system when the driving and dissipation are noncommutative. Then, the resulting stationary state does not obey the Floquet-Gibbs distribution, and the system dynamics is determined by inelastic scattering processes of the driving field.

Fast long-range charge transfer in quantum dot arrays.

Charge, spin and quantum states transfer in solid state devices is an important issue in quantum information. Adiabatic protocols, such as coherent transfer by adiabatic passage have been proposed for direct charge transfer, also denoted as long-range transfer, between the outer dots in a QD array without occupying the intermediate ones. However adiabatic protocols are prone to decoherence.

Transport, shot noise, and topology in AC-driven dimer arrays.

We analyze an AC-driven dimer chain connected to a strongly biased electron source and drain. It turns out that the resulting transport exhibits fingerprints of topology. They are particularly visible in the driving-induced current suppression and the Fano factor.

Radiation-induced resistance oscillations in a 2D hole gas: a demonstration of a universal effect.

We report on a theoretical study about the microwave-induced resistance oscillations and zero resistance states when dealing with p-type semiconductors and holes instead of electrons. We consider a high-mobility two-dimensional hole gas hosted in a pure Ge/SiGe quantum well. Similarly to electrons we obtain radiation-induced resistance oscillations and zero resistance states.

Realizing broadbands of strong nonlinear coupling in nanoelectromechanical electron shuttles.

We demonstrate the transition of a coupled electron shuttle from a stable to a strongly nonlinear response at room temperature. Within this transition we observe the coupled shuttle's response to change from Coulomb controlled to conventional field emission. This parametric process is fully reversible and occurs within a broad frequency range.

Steady-state coherent transfer by adiabatic passage.

We propose steady-state electron transport based on coherent transfer by adiabatic passage (CTAP) in a linearly arranged triple quantum dot with leads attached to the outer dots. Its main feature is repeated steering of single electrons from the first dot to the last dot without relevant occupation of the middle dot. The coupling to leads enables a steady-state current, whose shot noise is significantly suppressed provided that the CTAP protocol performs properly.

Microwave-induced resistance oscillations versus magnetoabsorption in two-dimensional electron systems: role of temperature.

Magnetoabsorption and microwave-induced resistance oscillations in two-dimensional electron systems are calculated with the same theoretical approach, the microwave-driven Larmor orbit model. This theory, which first was developed to obtain microwave-induced zero resistance states and resistance oscillations, permits us also to calculate the microwave magnetoabsorption. We study the influence of temperature on magnetoabsorption, obtaining a progressive quenching of the absorption peak as temperature increases.

Resonance fluorescence in transport through quantum dots: noise properties.

We study a two-level quantum dot embedded in a phonon bath and irradiated by a time-dependent ac field, and develop a method that allows us to extract simultaneously the full counting statistics of the electronic tunneling and relaxation (by phononic emission) events as well as their correlation. We find that the quantum noise of both the transmitted electrons and the emitted phonons can be controlled by the manipulation of external parameters such as the driving field intensity or the bias voltage.

ac-Driven double quantum dots as spin pumps and spin filters.

We propose and analyze a new scheme of realizing both spin filtering and spin pumping by using ac-driven double quantum dots in the Coulomb blockade regime. By calculating the current through the system in the sequential tunneling regime, we demonstrate that the spin polarization of the current can be controlled by tuning the parameters (amplitude and frequency) of the ac field. We also discuss spin relaxation and decoherence effects in the pumped current.

Nonequilibrium transport through double quantum dots: Kondo effect versus antiferromagnetic coupling.

We theoretically study the nonequilibrium transport properties of double quantum dots, in both series and parallel configurations. Our results lead to novel experimental predictions that unambiguously signal the transition from a Kondo state to an antiferromagnetic spin-singlet state, directly reflecting the physics of the two-impurity Kondo problem. We prove that the nonlinear conductance through parallel dots directly measures the exchange constant J between the spins of the dots.