Francesco Pietro Massel

• Brzezicki, Wojciech; Hyart, Timo & Massel, Francesco Pietro (2025). Non-Hermitian topology and entanglement in an optomechanical superlattice. Physical Review Research (PRResearch). 7(1). doi: 10.1103/PhysRevResearch.7.013089. Full text in Research Archive Show summary

  The interplay between topology and dissipation can give rise to a wealth of new phenomena and pave the way for novel topological lasers, sensors, and other quantum devices. Along these lines, we propose here an optomechanical setup in which the concomitant presence of a spatially modulated external drive and dissipation gives rise to a topologically nontrivial state for mechanical and optical excitations. We are able to show that the one-dimensional system considered here exhibits topologically protected end states for which mechanical and optical degrees of freedom are entangled. We show such entanglement to be robust with respect to the presence of nonzero-temperature baths and we propose a protocol for experimental observation of the entanglement.

• Stirpe, Davide; Manninen, Juuso & Massel, Francesco Pietro (2024). Semiclassical dynamics of a superconducting circuit: chaotic dynamics and fractal attractors. Physica Scripta. ISSN 0031-8949. 99(7). doi: 10.1088/1402-4896/ad4b6d. Full text in Research Archive
• Manninen, Juuso; Blick, Robert H. & Massel, Francesco Pietro (2024). Hybrid optomechanical superconducting qubit system. Physical Review Research (PRResearch). 6(2). doi: 10.1103/PhysRevResearch.6.023029. Full text in Research Archive Show summary

  We propose an integrated nonlinear superconducting device based on a nanoelectromechanical shuttle. The system can be described as a qubit coupled to a bosonic mode. The topology of the circuit gives rise to an adjustable qubit-mechanical coupling, allowing the experimenter to tune between linear and quadratic coupling in the mechanical degrees of freedom. Owing to its flexibility and potential scalability, the proposed setup represents an important step towards the implementation of bosonic error correction with mechanical elements in large-scale superconducting circuits. We give preliminary evidence of this possibility by discussing a simple state-swapping protocol that uses this device as a quantum memory element.

• Wang, Cheng; Banniard, Louise; Børkje, Kjetil; Massel, Francesco Pietro; Lepinay, Laure Mercier de & Sillanpää, Mika A. (2024). Ground-state cooling of a mechanical oscillator by a noisy environment. Nature Communications. 15(1). doi: 10.1038/s41467-024-51645-7. Full text in Research Archive Show summary

  Dissipation and the accompanying fluctuations are often seen as detrimental for quantum systems since they are associated with fast relaxation and loss of phase coherence. However, it has been proposed that a pure state can be prepared if external noise induces suitable downwards transitions, while exciting transitions are blocked. We demonstrate such a refrigeration mechanism in a cavity optomechanical system, where we prepare a mechanical oscillator in its ground state by injecting strong electromagnetic noise at frequencies around the red mechanical sideband of the cavity. The optimum cooling is reached with a noise bandwidth smaller than but on the order of the cavity decay rate. At higher bandwidths, cooling is less efficient as suitable transitions are not effectively activated. In the opposite regime where the noise bandwidth becomes comparable to the mechanical damping rate, damping follows the noise amplitude adiabatically, and the cooling is also suppressed.

• Banniard, Louise; Wang, Cheng; Stirpe, Davide; Børkje, Kjetil; Massel, Francesco Pietro & Lépinay, Laure Mercier de [Show all 7 contributors for this article] (2024). Optomechanics Driven by Noisy and Narrowband Fields. Journal of Low Temperature Physics. ISSN 0022-2291. 217, p. 720–734. doi: 10.1007/s10909-024-03220-z. Full text in Research Archive
• Brzezicki, Wojciech; Silveri, Matti; Płodzień, Marcin; Massel, Francesco Pietro & Hyart, Timo (2023). Non-Hermitian topological quantum states in a reservoir-engineered transmon chain. Physical review B (PRB). ISSN 2469-9950. 107(11). doi: 10.1103/PhysRevB.107.115146. Full text in Research Archive
• Manninen, Juuso; Laitinen, Antti; Massel, Francesco Pietro & Hakonen, Pertti (2022). Mechanical Detection of the de Haas-van Alphen Effect in Graphene. Nano Letters. ISSN 1530-6984. 22(24), p. 9869–9875. doi: 10.1021/acs.nanolett.2c02655. Full text in Research Archive Show summary

  In our work, we study the dynamics of a graphene Corbino disk supported by a gold mechanical resonator in the presence of a magnetic field. We demonstrate here that our graphene/gold mechanical structure exhibits a nontrivial resonance frequency dependence on the applied magnetic field, showing how this feature is indicative of the de Haas–van Alphen effect in the graphene Corbino disk. Relying on the mechanical resonances of the Au structure, our detection scheme is essentially independent of the material considered and can be applied for dHvA measurements on any conducting 2D material. In particular, the scheme is expected to be an important tool in studies of centrosymmetric transition metal dichalcogenide (TMD) crystals, shedding new light on hidden magnetization and interaction effects.

• Børkje, Kjetil; Massel, Francesco Pietro & Harris, Jack (2021). Nonclassical photon statistics in two-tone continuously driven optomechanics. Physical Review A (PRA). ISSN 2469-9926. 104(6). doi: 10.1103/PhysRevA.104.063507. Full text in Research Archive Show summary

  In cavity optomechanics, single-photon detection of Raman scattered photons can be a useful tool for observing nonclassical features of both radiation and motion. While this tool has been employed in experiments with pulsed laser driving of a cavity mode, it has not been readily accessible to experiments with continuous and constant laser driving. To address this, we present a study of a standard optomechanical system where the cavity mode is continuously driven at two different frequencies and where sideband photons are detected by single-photon detectors after frequency filtering the output from the cavity mode around its resonance frequency. We first derive the normalized second-order coherence associated with the detected photons and show that it contains signatures of the quantum nature of the mechanical mode which would be absent with only single-tone driving. To identify model-independent nonclassical features, we derive two inequalities for the sideband photon statistics that should be valid in any classical model of the system. We show that these inequalities are violated in the proposed setup. This is provided that the average phonon occupation number of the mechanical mode is sufficiently small, which in principle can be achieved through sideband cooling intrinsic to the setup. Violation of the first inequality means that there is no well-defined probability distribution of the Glauber-Sudarshan type for the cavity mode. In contrast, a violation of the second inequality means that there is no joint probability distribution for the cavity mode at two times separated by a finite interval, which originates from the noncommutativity of the motional quadratures of the mechanical mode. The proposed setup thus employs a mechanical oscillator in order to generate a steady-state source of nonclassical radiation.

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• Massel, Francesco Pietro (2024). Panel discussion: "Academia Meets Industry: Unlocking the Potential of Quantum Technology". Full text in Research Archive
• Massel, Francesco Pietro (2024). A Quantum World: From the Fabric of Reality to a Technological Revolution. Full text in Research Archive
• Massel, Francesco Pietro (2023). Panel discussion: "Quantum technologies: present and future". Full text in Research Archive

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