Lifeboat Foundation

True to form, a “strange metal” quantum material proved strangely quiet in recent quantum noise experiments at Rice University. Published this week in Science, the measurements of quantum charge fluctuations known as “shot noise” provide the first direct evidence that electricity seems to flow through strange metals in an unusual liquidlike form that cannot be readily explained in terms of quantized packets of charge known as quasiparticles.

“The noise is greatly suppressed compared to ordinary wires,” said Rice’s Doug Natelson, the study’s corresponding author. “Maybe this is evidence that quasiparticles are not well-defined things or that they’re just not there and charge moves in more complicated ways. We have to find the right vocabulary to talk about how charge can move collectively.”

The experiments were performed on nanoscale wires of a well-studied quantum critical material with a precise 1−2−2 ratio of ytterbium, rhodium and silicon (YbRh₂Si₂). The material contains a high degree of quantum entanglement that produces temperature-dependent behavior.

How are we so smart? We seem to be able to make process data with ease, doing tasks in seconds that take supercomputers much longer. Well, one thought is that we fundamentally take advantage of quantum mechanics to perform calculations similar to a quantum computer. This would give us a biologically produced quantum speed up in our brains. Until recently this was just a thought, there is no evidence that this is true. Well, now scientists believe that they may have found evidence of quantum interaction in our brains. Even more importantly, they showed that these quantum interactions are related to our consciousness. In this video, I discuss these latest results.

— References —
[1] https://iopscience.iop.org/article/10.1088/2399-6528/ac94be.
[2] https://phys.org/news/2022-10-brains-quantum.html.
[3] https://scitechdaily.com/shocking-experiment-indicates-our-b…mputation/

Continue reading “Are You Secretly A Quantum Computer?” »

In recent years, physicists have been trying to better understand how quantum information spreads in systems of interacting particles—a phenomenon often referred to as “scrambling.” Scrambling in closed systems, physical systems that can only exchange energy with degrees of freedom within the system, is a characteristic feature of chaotic many-body quantum dynamics.

In open systems, which can exchange both energy and matter with their surroundings, scrambling is influenced by various additional factors, including noise and errors. While the effects of these additional influences are well-documented, leading for example to decoherence, how they affect scrambling remains poorly understood.

Two researchers from the University of California Berkeley (UC Berkeley) and Harvard University recently introduced a new framework, published in Physical Review Letters, that provides a universal picture for how information scrambling occurs in open quantum systems. Their framework offers a particularly simple viewpoint on how to understand and model the propagation of errors in an open quantum system and might already help to explain some previously puzzling observations gathered in magnetic resonance experiments.

Ultra-short laser pulses may allow us to measure entanglement in a way that answers questions about the quantum nature of the vacuum.

By Karmela Padavic-Callaghan

IVO chief executive Richard Mansell said his company performed 100 hours of vacuum chamber testing before the launch, during which the quantum drive produced a small amount of thrust.

“Deploying Quantum Drive into orbit in a Rogue satellite on SpaceX Transporter 9 is a milestone for the future of space propulsion,” Mansell said.

“Quantum Drive’s capability allows Rogue to produce new satellite vehicles with unlimited Delta V.”

Pierre Agostini, Ferenc Krausz and Anne L’Huillier share the 2023 Nobel Prize in Physics for experiments that “have given humanity new tools for exploring the world of electrons inside atoms and molecules.” A more succinct description is that they have given us attosecond physics.

Attosecond physics is the science of the exceedingly, extremely, exceptionally [insert your own hyperbolic adverb here] fast. To put it into context, L’Huillier’s first call from the Nobel Prize’s Adam Smith after she received the news took 3 minutes 48 seconds, or-1 attoseconds. Her first heartbeat during that call lasted a second, or a billion billion attoseconds. Almost defying a description, an attosecond is an unfathomably tiny amount of time. But it happens to be the natural timescale of the near-instantaneous dance of electrons.

Continue reading “Nobel Prize in Phyiscs 2023” »

Three research groups have exploited the nuclear spins of ytterbium-171 to manipulate qubits before they are read out—an approach that could lead to efficient error-correction schemes for trapped-atom computing platforms.

Quantum computing on neutral-atom platforms has reached remarkable milestones in the past two decades. However, researchers have yet to overcome a key barrier to the realization of a neutral-atom-based quantum computer: the efficient correction of errors. In principle that barrier can be lowered with so-called midcircuit operations. These operations involve probing the quantum state of “ancilla” qubits without disturbing nearby “data” qubits used for computation. The ancilla qubit measurements can indicate whether the data qubits have undergone faulty operations, allowing for the data qubits to be corrected midcircuit—that is, during the execution of the computation rather than after its completion. Now three independent research groups have achieved midcircuit operation, or made progress toward this goal, with a novel choice of atom: ytterbium-171 (¹⁷¹ Yb) [1– 3].

A neutral-atom qubit platform consists of a two-dimensional (2D) array of atoms trapped by optical tweezers—tightly focused laser beams whose wavelengths are tuned far away from the atomic transitions. The size of the traps, limited by diffraction, is typically about 1 µm. Thanks to the large electric-dipole force from the focused laser and to a high vacuum, the atoms can stay trapped for as long as tens of seconds.

Heisenberg’s uncertainty principle limits the precision with which two observables that do not commute with each other can be simultaneously measured. The Wigner-Araki-Yanase (WAY) theorem goes further. If observables A and B do not commute, and if observable A is conserved, observable B cannot be measured with arbitrary precision even if A is not measured at all. In its original 1960 formulation, the WAY theorem applied only to observables, such as spin, whose possible values are discrete and bounded. Now Yui Kuramochi of Kyushu University and Hiroyasu Tajima of the University of Electro-Communications—both in Japan—have proven that the WAY theorem also encompasses observables, such as position, that are continuous and unbounded [1]. Besides resolving the decades-long problem of how to deal with such observables, the extension will likely find practical applications in quantum optics.

The difficulty of extending the WAY theorem arose from how an unbounded observable L is represented: as an infinite-dimensional matrix with unbounded eigenvalues. To tame the problem, Kuramochi and Tajima avoided considering L directly. Instead, they looked at an exponential function of L, which forms a one-parameter unitary group. Although the exponential function is also unbounded, its spectrum of eigenvalues is contained within the complex plane’s unit circle. Thanks to that boundedness, Kuramochi and Tajima could go on to use off-the-shelf techniques from quantum information to complete their proof.

Because momentum is conserved, the extended WAY theorem implies that a particle’s position cannot be measured with arbitrary precision even if its momentum is not measured simultaneously. Similar pairs of observables crop up in quantum optics. Kuramochi and Tajima anticipate that their theorem could be useful in setting limits on the extent to which quantum versions of transmission protocols can outperform the classical ones.

Light confined to an accelerating optical cavity could display a photonic counterpart of the electronic quantum Hall effect.

Place a conductor in a magnetic field and the electrical current driven by an applied voltage will not flow in a straight line but in a direction perpendicular to the electric field—a behavior known as the Hall effect [1]. Reduce the temperature to the point where the electrons manifest quantum-mechanical behavior, and the plot thickens. The conductivity (defined as the ratio between the sideways current and the voltage) exhibits discrete jumps as the magnetic field is varied—the quantum Hall effect [2]. Since electrons at low temperature and photons obey a similar wave equation [3], should we also expect a quantum Hall effect for light? This question has been bubbling under the surface for the past decade, leading to the observation of some aspects of an optical quantum Hall effect [4, 5]. But the analogy between photons and electrons remains incomplete.