@article{Braidotti2024,

title = {Amplification of electromagnetic fields by a rotating body},

author = {M. C. Braidotti and A. Vinante and M. Cromb and A. Sandakumar and D. Faccio and H. Ulbricht},

doi = {10.1038/s41467-024-49689-w},

issn = {2041-1723},

year  = {2024},

date = {2024-12-00},

journal = {Nat Commun},

volume = {15},

number = {1},

publisher = {Springer Science and Business Media LLC},

abstract = {AbstractIn 1971, Zel’dovich predicted the amplification of electromagnetic (EM) waves scattered by a rotating metallic cylinder, gaining mechanical rotational energy from the body. This phenomenon was believed to be unobservable with electromagnetic fields due to technological difficulties in meeting the condition of amplification that is, the cylinder must rotate faster than the frequency of the incoming radiation. Here, we measure the amplification of an electromagnetic field, generated by a toroid LC-circuit, scattered by an aluminium cylinder spinning in the toroid gap. We show that when the Zel’dovich condition is met, the resistance induced by the cylinder becomes negative implying amplification of the incoming EM fields. These results reveal the connection between the concept of induction generators and the physics of this fundamental physics effect and open new prospects towards testing the Zel’dovich mechanism in the quantum regime, as well as related quantum friction effects.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Sgroi2024,

title = {Efficient excitation-transfer across fully connected networks via local-energy optimization},

author = {S. Sgroi and G. Zicari and A. Imparato and M. Paternostro},

doi = {10.1140/epjqt/s40507-024-00238-w},

issn = {2196-0763},

year  = {2024},

date = {2024-12-00},

journal = {EPJ Quantum Technol.},

volume = {11},

number = {1},

publisher = {Springer Science and Business Media LLC},

abstract = {AbstractWe study the excitation transfer across a fully connected quantum network whose sites energies can be artificially designed. Starting from a simplified model of a broadly-studied physical system, we systematically optimize its local energies to achieve high excitation transfer for various environmental conditions, using an adaptive Gradient Descent technique and Automatic Differentiation. We show that almost perfect transfer can be achieved with and without local dephasing, provided that the dephasing rates are not too large. We investigate our solutions in terms of resilience against variations in either the network connection strengths, or size, as well as coherence losses. We highlight the different features of a dephasing-free and dephasing-driven transfer. Our work gives further insight into the interplay between coherence and dephasing effects in excitation-transfer phenomena across fully connected quantum networks. In turn, this will help designing optimal transfer in artificial open networks through the simple manipulation of local energies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Hanif2024,

title = {Testing Whether Gravity Acts as a Quantum Entity When Measured},

author = {Farhan Hanif and Debarshi Das and Jonathan Halliwell and Dipankar Home and Anupam Mazumdar and Hendrik Ulbricht and Sougato Bose},

doi = {10.1103/physrevlett.133.180201},

issn = {1079-7114},

year  = {2024},

date = {2024-10-00},

journal = {Phys. Rev. Lett.},

volume = {133},

number = {18},

publisher = {American Physical Society (APS)},

abstract = {A defining signature of classical systems is “in principle measurability” without disturbance: a feature manifestly violated by quantum systems. We describe a multi-interferometer experimental setup that can, in principle, reveal the nonclassicality of a spatial superposition-sourced gravitational field if an irreducible disturbance is caused by a measurement of gravity. While one interferometer sources the field, the others are used to measure the gravitational field created by the superposition. This requires neither any specific form of nonclassical gravity, nor the generation of entanglement between any relevant degrees of freedom at any stage, thus distinguishing it from the experiments proposed so far. This test, when added to the recent entanglement-witness based proposals, enlarges the domain of quantum postulates being tested for gravity. Moreover, the proposed test yields a signature of quantum measurement induced disturbance for any finite rate of decoherence, and is device independent.

          

            

            

              

                Published by the American Physical Society

                2024

              

            

          },

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Timberlake2024,

title = {Linear cooling of a levitated micromagnetic cylinder by vibration},

author = {Chris Timberlake and Elliot Simcox and Hendrik Ulbricht},

doi = {10.1103/physrevresearch.6.033345},

issn = {2643-1564},

year  = {2024},

date = {2024-09-00},

journal = {Phys. Rev. Research},

volume = {6},

number = {3},

publisher = {American Physical Society (APS)},

abstract = {We report feedback cooling of translational and librational degrees of freedom of a levitated m icromagnet cylinder, utilizing a piezoelectric actuator to apply linear feedback to high-Q mechanical modes. The normal modes are measured with a superconducting pick-up coil coupled to a dc SQUID, and phase information is fed back to the piezoelectric actuator to feedback cool a center-of-mass mode to ∼7K, and a librational mode to 830±200mK. Q-factors of 1.0×107 are evaluated for the center-of-mass mode. We find that it is plausible to achieve ground state cooling of the center-of-mass mode by introducing vibration isolation, optimizing the geometry of the pick-up coil to focus on the specific mode of interest and utilizing a state-of-the-art SQUID for detection.

          

            

            

              

                Published by the American Physical Society

                2024

              

            

          },

keywords = {},

pubstate = {published},

tppubtype = {article}

}