Stefano Bosco

Contact

Department of Physics
University of Basel
Klingelbergstrasse 82
CH-4056 Basel, Switzerland
office:4.7

email:view address

tel: +41 61 207 36 94


Short CV

2019 - present Postdoc, University of Basel, Switzerland with Prof. Daniel Loss
2015 - 2019 Ph.D. in Condensed matter physics, RWTH Aachen University, Germany
Supervisor: Prof. David P. DiVincenzo
2013 - 2015 M. Sc. in Nanoscience and Nanotechnology,
Erasmus Mundus in: Katholieke Universiteit Leuven, Belgium and Chalmers Tekniska Hogskola, Sweden.
2010 - 2013 Bachelor degree in Electronics Engineering, Politecnico di Milano, Italy.

Publications

Show all abstracts.

1.  Hole Spin Qubits in Ge Nanowire Quantum Dots: Interplay of Orbital Magnetic Field, Strain, and Growth Direction
Christoph Adelsberger, Mónica Benito, Stefano Bosco, Jelena Klinovaja, and Daniel Loss.
arXiv:2110.15039 (2021)



2.  Fully tunable hyperfine interactions of hole spin qubits in Si and Ge quantum dots
Stefano Bosco and Daniel Loss.
Phys. Rev. Lett. 127, 190501 (2021)



3.  Squeezed hole spin qubits in Ge quantum dots with ultrafast gates at low power
Stefano Bosco, Mónica Benito, Christoph Adelsberger, and Daniel Loss.
Phys. Rev. B 104, 115425 (2021)



4.  Hole Spin Qubits in Si FinFETs With Fully Tunable Spin-Orbit Coupling and Sweet Spots for Charge Noise
Stefano Bosco, Bence Hetényi, and Daniel Loss.
PRX Quantum 2, 010348 (2021)



5.  Strong spin-orbit interaction and g-factor renormalization of hole spins in Ge/Si nanowire quantum dots
F. N. M. Froning, M. J. Rančić, Bence Hetényi, Stefano Bosco, M. K. Rehmann, A. Li, E. P. A. M. Bakkers, F. A. Zwanenburg, Daniel Loss, D. M. Zumbühl, and F. R. Braakman.
Phys. Rev. Research 3, 013081 (2021)



6.  Hardware-Encoding Grid States in a Non-Reciprocal Superconducting Circuit
Martin Rymarz, Stefano Bosco, Alessandro Ciani, and David P. DiVincenzo.
Phys. Rev. X 11, 011032 (2021)



7.  Simulating moving cavities in superconducting circuits
Stefano Bosco, Joel Lindkvist, and Göran Johansson.
Phys. Rev. A 100, 023817 (2019)

We theoretically investigate the simulation of moving cavities in a superconducting circuit setup. In particular, we consider a recently proposed experimental scenario where the phase of the cavity field is used as a moving clock. By computing the error made when simulating the cavity trajectory with superconducting quantum interference devices (SQUIDs), we identify parameter regimes where the correspondence holds, and where time dilation and corrections due to clock size and to particle creation coefficients are observable. These findings may serve as a guideline when performing experiments on simulation of moving cavities in superconducting circuits.

8.  Transmission lines and resonators based on quantum Hall plasmonics: Electromagnetic field, attenuation, and coupling to qubits
Stefano Bosco and David P. DiVincenzo.
Phys. Rev. B 100, 035416 (2019)

Quantum Hall edge states have some characteristic features that can prove useful to measure and control solid state qubits. For example, their high voltage to current ratio and their dissipationless nature can be exploited to manufacture low-loss microwave transmission lines and resonators with a characteristic impedance of the order of the quantum of resistance h/e^2∼25kΩ. The high value of the impedance guarantees that the voltage per photon is high, and for this reason, high-impedance resonators can be exploited to obtain larger values of coupling to systems with a small charge dipole, e.g., spin qubits. In this paper, we provide a microscopic analysis of the physics of quantum Hall effect devices capacitively coupled to external electrodes. The electrical current in these devices is carried by edge magnetoplasmonic excitations and by using a semiclassical model, valid for a wide range of quantum Hall materials, we discuss the spatial profile of the electromagnetic field in a variety of situations of interest. Also, we perform a numerical analysis to estimate the lifetime of these excitations and, from the numerics, we extrapolate a simple fitting formula which quantifies the Q factor in quantum Hall resonators. We then explore the possibility of reaching the strong photon-qubit coupling regime, where the strength of the interaction is higher than the losses in the system. We compute the Coulomb coupling strength between the edge magnetoplasmons and singlet-triplet qubits, and we obtain values of the coupling parameter in the order of 100 MHz; comparing these values to the estimated attenuation in the resonator, we find that for realistic qubit designs the coupling can indeed be strong.

9.  Transmission Lines and Metamaterials Based on Quantum Hall Plasmonics
Stefano Bosco, David P. DiVincenzo, and David J. Reilly.
Phys. Rev. Applied 12, 014030 (2019)

The characteristic impedance of a microwave transmission line is typically constrained to a value Z0=50Ω, in part because of the low impedance of free space and the limited range of permittivity and permeability realizable with conventional materials. Here we suggest the possibility of constructing high-impedance transmission lines by exploiting the plasmonic response of edge states associated with the quantum Hall effect in gated devices. We analyze various implementations of quantum Hall transmission lines based on distributed networks and lumped-element circuits, including a detailed account of parasitic capacitance and Coulomb drag effects, which can modify device performance. We additionally conceive of a metamaterial structure comprising arrays of quantum Hall droplets and analyze its unusual properties. The realization of such structures holds promise for efficiently wiring-up quantum circuits on chip, as well as engineering strong coupling between semiconductor qubits and microwave photons.

10.  Nonreciprocal quantum Hall devices with driven edge magnetoplasmons in two-dimensional materials
Stefano Bosco and David P. DiVincenzo.
Phys. Rev. B 95, 195317 (2017)

We develop a theory that describes the response of nonreciprocal devices employing two-dimensional materials in the quantum Hall regime capacitively coupled to external electrodes. As the conduction in these devices is understood to be associated to the edge magnetoplasmons (EMPs), we first investigate the EMP problem by using the linear response theory in the random phase approximation. Our model can incorporate several cases that were often treated on different grounds in literature. In particular, we analyze plasmonic excitations supported by a smooth and sharp confining potential in a two-dimensional electron gas, and in monolayer graphene, and we point out the similarities and differences in these materials. We also account for a general time-dependent external drive applied to the system. Finally, we describe the behavior of a nonreciprocal quantum Hall device: the response contains additional resonant features, which were not foreseen from previous models.

11.  Self-Impedance-Matched Hall-Effect Gyrators and Circulators
Stefano Bosco, Federica Haupt, and David P. DiVincenzo.
Phys. Rev. Applied 7, 024030 (2017)

We present a model study of an alternative implementation of a two-port Hall-effect microwave gyrator. Our setup involves three electrodes, one of which acts as a common ground for the others. Based on the capacitive-coupling model of Viola and DiVincenzo, we analyze the performance of the device and we predict that ideal gyration can be achieved at specific frequencies. Interestingly, the impedance of the three-terminal gyrator can be made arbitrarily small for certain coupling strengths, so that no auxiliary impedance matching is required. Although the bandwidth of the device shrinks as the impedance decreases, it can be improved by reducing the magnetic field; it can be realistically increased up to 150 MHz at 50Ω by working at the filling factor ν=10. We also examine the effects of the parasitic capacitive coupling between electrodes and we find that, although, in general, they strongly influence the response of device, their effect is negligible at low impedance. Finally, we analyze an interferometric implementation of a circulator, which incorporates the gyrator in a Mach-Zender–like construction. Perfect circulation in both directions can be achieved, depending on frequency and on the details of the interferometer.

12.  A model study of present-day Hall-effect circulators
Benedikt Placke, Stefano Bosco, and David P. DiVincenzo.
EPJ Quantum Technol. 4, 5 (2017)

Stimulated by the recent implementation of a three-port Hall-effect microwave circulator of Mahoney et al. (MEA), we present model studies of the performance of this device. Our calculations are based on the capacitive-coupling model of Viola and DiVincenzo (VD). Based on conductance data from a typical Hall-bar device obtained from a two-dimensional electron gas (2DEG) in a magnetic field, we numerically solve the coupled field-circuit equations to calculate the expected performance of the circulator, as determined by the S parameters of the device when coupled to 50Ω ports, as a function of frequency and magnetic field. Above magnetic fields of 1.5 T, for which a typical 2DEG enters the quantum Hall regime (corresponding to a Landau-level filling fraction ν of 20), the Hall angle θH=tan−1σxy/σxx always remains close to 90°, and the S parameters are close to the analytic predictions of VD for θH=π/2. As anticipated by VD, MEA find the device to have rather high (kΩ) impedance, and thus to be extremely mismatched to 50Ω, requiring the use of impedance matching. We incorporate the lumped matching circuits of MEA in our modeling and confirm that they can produce excellent circulation, although confined to a very small bandwidth. We predict that this bandwidth is significantly improved by working at lower magnetic field when the Landau index is high, e.g. ν=20, and the impedance mismatch is correspondingly less extreme. Our modeling also confirms the observation of MEA that parasitic port-to-port capacitance can produce very interesting countercirculation effects.