Events
Condensed Matter Seminar
Experimentally testing the spontaneous disentanglement hypothesis using a magnetic resonator
Prof. Eyal Buks
Technion
Mon, 21 Apr 2025, 11:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: The spontaneous disentanglement hypothesis is motivated by two outstanding issues in the foundations
of quantum mechanics (QM). The first one originates from the collapse postulate. This postulate
arguably gives rise to an internal inconsistency in QM [1], which was first introduced in 1935 by
Schrodinger [2], and which is commonly known as the problem of quantum measurement. Moreover,
the spontaneous disentanglement hypothesis is relevant to an apparent conflict between linearity of
standard QM, and experimental observations of multi–stabilities and phase transitions in finite quantum
systems.
The hypothesis that disentanglement spontaneously occurs in quantum systems is experimentally tested
using a ferrimagnetic resonator. According to this hypothesis, time evolution is governed by a modified
master equation having an added nonlinear term, which deterministically generates disentanglement.
The added term can give rise to multistabilities, which are otherwise theoretically excluded. Bistability is
experimentally observed in the resonator’s response to an externally applied monochromatic driving [3].
Experimental results are compared with predictions derived from the disentanglement–based model,
and an alternative model, which is based on the method of Bosonization and the Holstein–Primakoff
transformation. It is found that better agreement with data is obtained from the
disentanglement–based model. This finding, together with a difficulty to justify the Bosonization–based
model, indirectly support the spontaneous disentanglement hypothesis.
[1] Roger Penrose, “Uncertainty in quantum mechanics: faith or fantasy?”, Philosophical Transactions of
the Royal Society A: Mathematical, Physical and Engineering Sciences 369, 4864 (2011).
[2] E. Schrodinger, “Die gegenwartige situation in der quantenmechanik”, Naturwissenschaften 23,
807(1935).
[3] “Disentanglement–induced bistability in a magnetic resonator”, Advanced Quantum Technologies,
2400587 (2025).
Particles and Fields Seminar
Observation of the quantum equivalence principle for matter-waves
Prof. Ron Folman
BGU
Mon, 21 Apr 2025, 14:00
Sacta-Rashi Building for Physics (54), room 207
Abstract: Einstein's general theory of relativity is based on the principle of equivalence - in essence, dating back to Galileo - which asserts that, locally, the effect of a gravitational field is equivalent to that of an accelerating reference frame, so that the local gravitational field is eliminated in a freely falling frame. Einstein's theory enables this principle to extend to a global description of relativistic space-time, at the expense of allowing space-time to become curved, realising a consistent frame-independent description of nature at the classical level. Einstein's theory has been confirmed to great accuracy for astrophysical bodies. However, in the quantum domain the equivalence principle involves a gauge phase that is observable if the wavefunction - fundamental to quantum descriptions - allows an object to interfere with itself after being simultaneously at rest in two differently accelerating frames, one being the laboratory (Newtonian) frame and the other in the freely-falling (Einsteinian) frame. This is done with a novel cold-atom interferometer in which one wave packet stays static in the laboratory frame while the other is in free-fall. We follow the relative-phase evolution of the wave packets in the two frames, confirming the equivalence principle in the quantum domain. Our observation is yet another fundamental test of the interface between quantum theory and gravity. The new interferometer also opens the door for further probing of the latter interface, as well as to searches for new physics. [1]
[1] Or Dobkowski, Barak Trok, Peter Skakunenko, Yonathan Japha, David Groswasser, Maxim Efremov, Chiara Marletto, Ivette Fuentes, Roger Penrose, Vlatko Vedral, Wolfgang P. Schleich, Ron Folman, [2502.14535] Observation of the quantum equivalence principle for matter-waves (2025)
Physics Colloquium
The Fundamental Physics of the Onset of Frictional Motion: How does friction start?
Jay Fineberg
Hebrew University
Tue, 22 Apr 2025, 12:00
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015
Abstract: Recent experiments have demonstrated that rapid rupture fronts, akin to earthquakes, are responsible for the transition to frictional motion. These dynamic rupture fronts ("laboratory earthquakes") have a singular form whose dynamics are well-described by the theory that describes the physics of how things break – or fracture mechanics. Ruptures, however, need to be created within initially rough frictional interfaces, before they are able to propagate. This is the reason that "static friction coefficients" are not well-defined; frictional ruptures can nucleate for a wide range of applied forces. A critical open question is, he therefore, how the nucleation of rupture fronts actually takes place. We experimentally demonstrate that rupture front nucleation is prefaced by slow nucleation fronts. These nucleation fronts, which are self-similar, are not described by our current understanding of fracture mechanics. The nucleation fronts emerge from initially rough frictional interfaces at well-defined stress thresholds, evolve at characteristic velocity and time scales governed by stress levels, and propagate within a frictional interface to form the initial rupture from which fracture mechanics take over. These results are of fundamental importance to questions ranging from earthquake nucleation and prediction to processes governing material failure.
Physics Colloquium
TBA
Guy Bartal
Technion
Tue, 29 Apr 2025, 12:00
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015
Abstract:
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