62 research outputs found
Superconducting Josephson-Based Metamaterials for Quantum-Limited Parametric Amplification: A Review
In the last few years, several groups have proposed and developed their own platforms demonstrating quantum-limited linear parametric amplification, with evident applications in quantum information and computation, electrical and optical metrology, radio astronomy, and basic physics concerning axion detection. Here, we propose a short review on the physics behind parametric amplification via metamaterials composed by coplanar waveguides embedding several Josephson junctions. We present and compare different schemes that exploit the nonlinearity of the Josephson current-phase relation to mix the so-called signal, idler, and pump tones. The chapter then presents and compares three different theoretical models, developed in the last few years, to predict the dynamics of these nonlinear systems in the particular case of a 4-wave mixing process and under the degenerate undepleted pump assumption. We will demonstrate that, under the same assumption, all the results are comparable in terms of amplification of the output fields
Development of a PJVS System for Quantum-Based Sampled Power Measurements
The paper deals with recent progresses at INRiM towards the development and characterization of a programmable Josephson voltage standard (PJVS) operating in a small liquid helium dewar as well as with its integration for the realization of a practical quantum sampling electrical power standard. The
PJVS is based on a 1V superconductor-normal metal-superconductor (SNS) binary-divided array of 8192 Josephson junctions. To ensure proper operating conditions of the PJVS chip, a custom short cryoprobe was designed, built and successfully tested. The overall system is being developed in the framework of EMPIR project 19RPT01-QuantumPower. The goal is to establish a new quantum power standard (QPS) based on a single Josephson voltage standard for sampled power measurements and to gain confidence
in running PJVS for precise calibration of digital sampling multimeters and arbitrary waveform digitizers used in the ac-voltage and power metrology community
A quantum model for rf-SQUIDs based metamaterials enabling 3WM and 4WM Travelling Wave Parametric Amplification
A quantum model for Josephson-based metamaterials working in the Three-Wave
Mixing (3WM) and Four-Wave Mixing (4WM) regimes at the single-photon level is
presented. The transmission line taken into account, namely Traveling Wave
Josephson Parametric Amplifier (TWJPA), is a bipole composed by a chain of
rf-SQUIDs which can be biased by a DC current or a magnetic field in order to
activate the 3WM or 4WM nonlinearities. The model exploits a Hamiltonian
approach to analytically determine the time evolution of the system both in the
Heisenberg and interaction pictures. The former returns the analytic form of
the gain of the amplifier, while the latter allows recovering the probability
distributions vs. time of the photonic populations, for multimodal Fock and
coherent input states. The dependence of the metamaterial's nonlinearities is
presented in terms of circuit parameters in a lumped model framework while
evaluating the effects of the experimental conditions on the model validity
Newly-generated cells from the rostral migratory stream in the accessory olfactory bulb of the adult rat.
Carnosine-like immunoreactivity in atrocytes of the glial tubes and in newly-generated cells within the tangential part of the rostral migratory stream of rodents.
Semaphorin 4D regulates gonadotropin hormone–releasing hormone-1 neuronal migration through PlexinB1–Met complex
In mammals, reproduction is dependent on specific neurons secreting the neuropeptide gonadotropin hormone–releasing hormone-1 (GnRH-1). These cells originate during embryonic development in the olfactory placode and migrate into the forebrain, where they become integral members of the hypothalamic–pituitary–gonadal axis. This migratory process is regulated by a wide range of guidance cues, which allow GnRH-1 cells to travel over long distances to reach their appropriate destinations. The Semaphorin4D (Sema4D) receptor, PlexinB1, is highly expressed in the developing olfactory placode, but its function in this context is still unknown. Here, we demonstrate that PlexinB1-deficient mice exhibit a migratory defect of GnRH-1 neurons, resulting in reduction of this cell population in the adult brain. Moreover, Sema4D promotes directional migration in GnRH-1 cells by coupling PlexinB1 with activation of the Met tyrosine kinase (hepatocyte growth factor receptor). This work identifies a function for PlexinB1 during brain development and provides evidence that Sema4D controls migration of GnRH-1 neurons
High kinetic inductance NbTiN films for quantum limited travelling wave parametric amplifiers
A wide-bandwidth and low-noise amplification chain in the microwave regime is
crucial for the efficient read-out of quantum systems based on superconducting
detectors, such as Microwave Kinetic Inductance Detectors (MKIDs), Transition
Edge Sensors (TESs), Magnetic Microcalorimeters (MMCs), and RF cavities, as
well as qubits. Kinetic Inductance Travelling Wave Parametric Amplifiers
(KI-TWPAs) operated in a three-wave mixing fashion have demonstrated
exceptional dynamic range and low-noise performance, approaching the quantum
limit. These amplifiers can be fabricated using a single layer of a high
kinetic inductance film as weakly dispersive artificial transmission lines,
with the ability to control the phase-matched bandwidth through dispersion
engineering. In this study, we present the optimisation of the rf
sputter-deposition process of NbTiN films using a Nb80%T20 target, with the
goal of achieving precise control over film characteristics, resulting in high
kinetic inductance while maintaining a high transition temperature. The
parameter landscape related to the different sputtering conditions, such as
pressure, power, and nitrogen flow, has been explored and the film thickness
has been used as a fine-tuning parameter to adjust the properties of the final
NbTiN films used for the fabrication of KI-TWPAs. As a final result, we have
obtained a NbTiN film with a kinetic inductance of 8.5 pH/sq which we have
exploited to fabricate KI-TWPA prototype devices, showing promising
amplification performance
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