arXiv subjects

Michaël Simoen

Publications and source records attributed to Michaël Simoen.

4 recordsLinked to original sources

arXiv2018

Nondegenerate parametric oscillations in a tunable superconducting resonator

We investigate nondegenerate parametric oscillations in a multimode superconducting microwave resonator that is terminated by a SQUID. The parametric effect is achieved by modulating magnetic flux through the SQUID at a frequency close to the sum of two resonator-mode frequencies. For modulation amplitudes exceeding an instability threshold, self-sustained oscillations are observed in both modes. The amplitudes of these oscillations show good quantitative agreement with a theoretical model. The oscillation phases are found to be correlated and exhibit strong fluctuations which broaden the oscillation spectral linewidths. These linewidths are significantly reduced by applying a weak on-resonance tone, which also suppresses the phase fluctuations. When the weak tone is detuned, we observe synchronization of the oscillation frequency with the frequency of the input. For the detuned input, we also observe an emergence of three idlers in the output. This observation is in agreement with theory indicating four-mode amplification and squeezing of a coherent input.

quant-ph↗

arXiv2017

Microwave photon generation in a doubly tunable superconducting resonator

We have developed and tested a doubly tunable resonator, with the intention to simulate fast motion of the resonator boundaries in real space. Our device is a superconducting coplanar-waveguide half-wavelength microwave resonator, with fundamental resonant frequency ~5 GHz. Both of its ends are terminated by dc-SQUIDs, which serve as magnetic-flux-controlled inductances. Applying a flux to either SQUID allows tuning of the resonant frequency by approximately 700 MHz. By using two separate on-chip magnetic-flux lines, we modulate the SQUIDs with two tones of equal frequency, close to twice that of the resonator's fundamental mode. We observe photon generation, at the fundamental frequency, above a certain pump amplitude threshold. By varying the relative phase of the two pumps we are able to control the photon generation threshold, in good agreement with a theoretical model for the modulation of the boundary conditions. At the same time, some of our observations deviate from the theoretical predictions, which we attribute to parasitic couplings, resulting in current driving of the SQUIDs.

cond-mat.mes-hall↗

arXiv2016

Simple, robust and on-demand generation of single and correlated photons

We propose two different setups to generate single photons on demand using an atom in front of a mirror, along with either a beam-splitter or a tunable coupling. We show that photon generation efficiency ~99% is straightforward to achieve. The proposed schemes are simple and easily tunable in frequency. The operation is relatively insensitive to dephasing and can be easily extended to generate correlated pairs of photons. They can also in principle be used to generate any photonic qubit of the form $μ|0 \rangle + ν|1\rangle$ in arbitrary wave-packets, making them very attractive for quantum communication applications.

quant-ph↗

arXiv2016

Single-shot Readout of a Superconducting Qubit using a Josephson Parametric Oscillator

We propose and demonstrate a new read-out technique for a superconducting qubit by dispersively coupling it to a Josephson parametric oscillator. We employ a tunable quarter-wavelength superconducting resonator and modulate its resonant frequency at twice its value with an amplitude surpassing the threshold for parametric instability. We map the qubit states onto two distinct states of classical parametric oscillation: one oscillating state, with $185\pm15$ photons in the resonator, and one with zero oscillation amplitude. This high contrast obviates a following quantum-limited amplifier. We demonstrate proof-of-principle, single-shot readout performance, and present an error budget indicating that this method can surpass the fidelity threshold required for quantum computing.

quant-ph↗