arXiv subjects

M. Filippone

Publications and source records attributed to M. Filippone.

7 recordsLinked to original sources

arXiv2026

Spin-cQED with bulk germanium spin qubits

Unstrained bulk germanium is a particularly attractive material for circuit quantum electrodynamics with spins (spin-cQED). We show, through systematic modeling and comparison with state-of-the-art strained germanium heterostructures, that hole spins in bulk germanium double quantum dots readily reach the strong-coupling regime with superconducting microwave resonators, achieving spin-photon coupling strengths $g_s/2\pi\gtrsim100$\,MHz. This enhancement originates from large spin-orbit interactions beyond the perturbative regime. In addition, the coupling is much less sensitive to the orientation of the applied magnetic field, which shall ease operation and limit the impact of device-to-device variability. Our results establish bulk germanium as a compelling platform for scalable spin-cQED.

cond-mat.mes-hall↗

arXiv2024

Measuring Hall voltage and Hall resistance in an atom-based quantum simulator

In the Hall effect, a voltage drop develops perpendicularly to the current flow in the presence of a magnetic field, leading to a transverse Hall resistance. Recent developments with quantum simulators have unveiled strongly correlated and universal manifestations of the Hall effect. However, a direct measurement of the Hall voltage and of the Hall resistance in a non-electronic system of strongly interacting fermions was not achieved to date. Here, we demonstrate a technique for measuring the Hall voltage in a neutral-atom-based quantum simulator. From that we provide the first direct measurement of the Hall resistance in a cold-atom analogue of a solid-state Hall bar and study its dependence on the carrier density, along with theoretical analyses. Our work closes a major gap between analogue quantum simulations and measurements performed in solid-state systems, providing a key tool for the exploration of the Hall effect in highly tunable and strongly correlated systems.

cond-mat.quant-gas↗

arXiv2022

Observation of Universal Hall Response in Strongly Interacting Fermions

The Hall effect, which originates from the motion of charged particles in magnetic fields, has deep consequences for the description of materials, extending far beyond condensed matter. Understanding such an effect in interacting systems represents a fundamental challenge, even for small magnetic fields. In this work, we used an atomic quantum simulator in which we tracked the motion of ultracold fermions in two-leg ribbons threaded by artificial magnetic fields. Through controllable quench dynamics, we measured the Hall response for a range of synthetic tunneling and atomic interaction strengths. We unveil a universal interaction-independent behavior above an interaction threshold, in agreement with theoretical analyses. The ability to reach hard-to-compute regimes demonstrates the power of quantum simulation to describe strongly correlated topological states of matter.

cond-mat.quant-gas↗

arXiv2022

Tunable hole spin-photon interaction based on g-matrix modulation

We consider a spin circuit-QED device where a superconducting microwave resonator is capacitively coupled to a single hole confined in a semiconductor quantum dot. Thanks to the strong spin-orbit coupling intrinsic to valence-band states, the gyromagnetic g-matrix of the hole can be modulated electrically. This modulation couples the photons in the resonator to the hole spin. We show that the applied gate voltages and the magnetic-field orientation enable a versatile control of the spin-photon interaction, whose character can be switched from fully transverse to fully longitudinal. The longitudinal coupling is actually maximal when the transverse one vanishes and vice-versa. This "reciprocal sweetness" results from geometrical properties of the g-matrix and protects the spin against dephasing or relaxation. We estimate coupling rates reaching ~ 10 MHz in realistic settings and discuss potential circuit-QED applications harnessing either the transverse or the longitudinal spin-photon interaction. Furthermore, we demonstrate that the g-matrix curvature can be used to achieve parametric longitudinal coupling with enhanced coherence.

cond-mat.mes-hall↗

arXiv2019

Direct measurement of non-local interactions in the many-body localized phase

The interplay of interactions and strong disorder can lead to an exotic quantum many-body localized (MBL) phase. Beyond the absence of transport, the MBL phase has distinctive signatures, such as slow dephasing and logarithmic entanglement growth; they commonly result in slow and subtle modification of the dynamics, making their measurement challenging. Here, we experimentally characterize these properties of the MBL phase in a system of coupled superconducting qubits. By implementing phase sensitive techniques, we map out the structure of local integrals of motion in the MBL phase. Tomographic reconstruction of single and two qubit density matrices allowed us to determine the spatial and temporal entanglement growth between the localized sites. In addition, we study the preservation of entanglement in the MBL phase. The interferometric protocols implemented here measure affirmative correlations and allow us to exclude artifacts due to the imperfect isolation of the system. By measuring elusive MBL quantities, our work highlights the advantages of phase sensitive measurements in studying novel phases of matter.

cond-mat.dis-nn↗

arXiv2013

Probabilistic prediction of neurological disorders with a statistical assessment of neuroimaging data modalities

For many neurological disorders, prediction of disease state is an important clinical aim. Neuroimaging provides detailed information about brain structure and function from which such predictions may be statistically derived. A multinomial logit model with Gaussian process priors is proposed to: (i) predict disease state based on whole-brain neuroimaging data and (ii) analyze the relative informativeness of different image modalities and brain regions. Advanced Markov chain Monte Carlo methods are employed to perform posterior inference over the model. This paper reports a statistical assessment of multiple neuroimaging modalities applied to the discrimination of three Parkinsonian neurological disorders from one another and healthy controls, showing promising predictive performance of disease states when compared to nonprobabilistic classifiers based on multiple modalities. The statistical analysis also quantifies the relative importance of different neuroimaging measures and brain regions in discriminating between these diseases and suggests that for prediction there is little benefit in acquiring multiple neuroimaging sequences. Finally, the predictive capability of different brain regions is found to be in accordance with the regional pathology of the diseases as reported in the clinical literature.

stat.AP↗

arXiv2011

Quantum phase transitions in fully connected spin models: an entanglement perspective

We consider a set of fully connected spins models that display first- or second-order transitions and for which we compute the ground-state entanglement in the thermodynamical limit. We analyze several entanglement measures (concurrence, Rényi entropy, and negativity), and show that, in general, discontinuous transitions lead to a jump of these quantities at the transition point. Interestingly, we also find examples where this is not the case.

cond-mat.stat-mech↗