Lifeboat Foundation

We use two 1D quasicondensates in a double potential well to realize a bosonic Josephson junction, a microscopic system that gives rise to interesting quantum phenomena resulting from the interplay of quantum tunneling and interaction. The multimode characteristics within the quasicondensates make the system suitable as a quantum field simulator. To prepare quantum states, we split a single condensate into two and, consequently, we witness the dynamical evolution of quantum fluctuations in the relative degree of freedom between the two split condensates. We demonstrate how to use these dynamics to effectively prepare more strongly correlated quantum states and how those influence spatial phase coherence.

Our work introduces innovative methods for engineering correlations and entanglement in the external degree of freedom of interacting many-body systems. It is a leap forward in understanding and harnessing quantum correlations, paving the way for exciting possibilities in quantum simulation research.

Everybody involved has long known that some math problems are too hard to solve (at least without unlimited time), but a proposed solution could be rather easily verified. Suppose someone claims to have the answer to such a very hard problem. Their proof is much too long to check line by line. Can you verify the answer merely by asking that person (the “prover”) some questions? Sometimes, yes. But for very complicated proofs, probably not. If there are two provers, though, both in possession of the proof, asking each of them some questions might allow you to verify that the proof is correct (at least with very high probability). There’s a catch, though — the provers must be kept separate, so they can’t communicate and therefore collude on how to answer your questions. (This approach is called MIP, for multiprover interactive proof.)

Verifying a proof without actually seeing it is not that strange a concept. Many examples exist for how a prover can convince you that they know the answer to a problem without actually telling you the answer. A standard method for coding secret messages, for example, relies on using a very large number (perhaps hundreds of digits long) to encode the message. It can be decoded only by someone who knows the prime factors that, when multiplied together, produce the very large number. It’s impossible to figure out those prime numbers (within the lifetime of the universe) even with an army of supercomputers. So if someone can decode your message, they’ve proved to you that they know the primes, without needing to tell you what they are.

Yes, say researchers who experimentally executed a protocol designed to do just that.

In hindsight, it seems prophetic that the title of a Nature paper published on 1 March 1974 ended with a question mark: “Black hole explosions?” Stephen Hawking’s landmark idea about what is now known as Hawking radiation¹ has just turned 50. The more physicists have tried to test his theory over the past half-century, the more questions have been raised — with profound consequences for how we view the workings of reality.

In essence, what Hawking, who died six years ago today, found is that black holes should not be truly black, because they constantly radiate a tiny amount of heat. That conclusion came from basic principles of quantum physics, which imply that even empty space is a far-from-uneventful place. Instead, space is filled with roiling quantum fields in which pairs of ‘virtual’ particles incessantly pop out of nowhere and, under normal conditions, annihilate each other almost instantaneously.

However, at an event horizon, the spherical surface that defines the boundary of a black hole, something different happens. An event horizon represents a gravitational point of no return that can be crossed only inward, and Hawking realized that there two virtual particles can become separated. One of them falls into the black hole, while the other radiates away, carrying some of the energy with it. As a result, the black hole loses a tiny bit of mass and shrinks — and shines.

A technique called time-and angle-resolved photoemission spectroscopy (TR-ARPES) has emerged as a powerful tool, allowing researchers to explore the equilibrium and dynamical properties of quantum materials via light-matter interaction.

Physicists at the University of Regensburg have choreographed the shift of a quantized electronic energy level with atomic oscillations faster than a trillionth of a second.

Throwing a ball into the air, one can transfer arbitrary energy to the ball such that it flies higher or lower. One of the oddities of quantum physics is that particles, e.g., electrons, can often only take on quantized energy values—as if the ball was leaping between specific heights, like steps of a ladder, rather than flying continuously.

Qubits and quantum computers as well as light-emitting quantum dots (Nobel Prize 2023) make use of this principle. However, electronic energy levels can be shifted by collisions with other electrons or atoms. Processes in the quantum world usually take place on atomic scales and are also incredibly fast.

Researchers at the Department of Energy’s Oak Ridge National Laboratory have demonstrated that advanced quantum-based cybersecurity can be realized in a deployed fiber link.

Researchers at ETH have managed to trap ions using static electric and magnetic fields and to perform quantum operations on them. In the future, such traps could be used to realize quantum computers with far more quantum bits than have been possible up to now.

Electronic states that resemble molecules and are promising for use in future quantum computers have been created in superconducting circuits by physicists at RIKEN.