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Team studies the emergence of fluctuating hydrodynamics in chaotic quantum systems

Researchers at Ludwig-Maximilians-Universität, Max-Planck-Institut für Quantenoptik, Munich Center for Quantum Science and Technology (MCQST) and the University of Massachusetts recently carried out a study investigating the equilibrium fluctuations in large quantum systems. Their paper, published in Nature Physics, outlines the results of large-scale quantum simulations performed using a quantum gas microscope, an experimental tool used to image and manipulate individual atoms in ultracold atomic gases.

Ephos raises $8.5M to transform quantum computing and AI with its glass-based quantum photonic chips

A Milan-based deep tech startup, Ephos, raised $8.5M in a seed round led by Starlight Ventures to accelerate the development of its glass-based quantum photonic chips. The company aims to transform not just quantum computing and AI but also the broader computational infrastructure of the future.

Other participants included Collaborative Fund, Exor Ventures, 2100 Ventures, and Unruly Capital. The round also attracted angel investors such as Joe Zadeh, former Vice President at Airbnb; Diego Piacentini, former Senior Vice President at Amazon; and Simone Severini, General Manager of Quantum Technologies at Amazon Web Services.

In addition to private investment, Ephos received funding from the European Innovation Council (EIC) and €450,000 in non-dilutive financing from NATO’s Defence Innovation Accelerator (DIANA).

Thermodynamics of frozen stars

New study suggests that black holes may not be the featureless, structureless entities that Einstein’s general theory of relativity predicts them to be.


The frozen star is a recent proposal for a nonsingular solution of Einstein’s equations that describes an ultracompact object which closely resembles a black hole from an external perspective. The frozen star is also meant to be an alternative, classical description of an earlier proposal, the highly quantum polymer model. Here, we show that the thermodynamic properties of frozen stars closely resemble those of black holes: frozen stars radiate thermally, with a temperature and an entropy that are perturbatively close to those of black holes of the same mass. Their entropy is calculated using the Euclidean-action method of Gibbons and Hawking. We then discuss their dynamical formation by estimating the probability for a collapsing shell of “normal’’ matter to transition, quantum mechanically, into a frozen star.

Disorder Induces Delocalization

A Bose-Einstein condensate of cold atoms occupying a periodic lattice can flow like a superfluid. But if the atoms’ mutual repulsion is strengthened and the lattice potential deepened, the atoms can become immobilized in a state known as a Mott insulator. Now Hepeng Yao of the University of Geneva and his collaborators have examined the Mott transition of cold atoms trapped in a lattice that is quasiperiodic rather than periodic [1]. Given that quasiperiodicity and other kinds of disorder tend to trap particles, the researchers were surprised to discover that their quasiperiodic lattice sustained the superfluid state rather than weakening it.

Yao and his collaborators trapped potassium-39 atoms in a one-dimensional optical lattice formed by the standing waves of two lasers. If the ratio of the lasers’ wavelengths was a rational number, the lattice was periodic. Otherwise, the lattice was quasiperiodic. By adjusting various experimental parameters, they could control the depth of the confining potentials, the strength of the interatomic repulsion, and whether the lattice sites were fully occupied. To determine whether a given set of parameters yielded a static, insulating state or a mobile, superfluid one, they turned off the trap and observed how the atoms flew apart.

The team found that the Mott transitions for the periodic and quasiperiodic lattices were both characterized by a critical value of the interparticle repulsion, but the critical value in the quasiperiodic case was higher. Quantum Monte Carlo simulations pointed to the reason. The commensurability between the lattice period and the particle number is a key factor in pinning particles in a Mott insulator. However, the quasiperiodic lattice blurs this commensurate period, thereby destabilizing the Mott phase to the profit of the superfluid one.

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