Lifeboat Foundation

Physicists are (temporarily) augmenting reality in order to crack the code of quantum systems.

Calculating the collective behavior of a molecule’s electrons is necessary to predict a material’s properties. Such predictions could one day help scientists create novel drugs or create materials with desirable qualities like superconductivity. The issue is that electrons may become ‘quantum mechanically’ entangled with one another, which means they can no longer be treated individually. For any system with more than a few particles, the entangled network of connections becomes outrageously difficult for even the most powerful computers to unravel directly.

Now, quantum physicists from the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland and the Flatiron Institute’s Center for Computational Quantum Physics (CCQ) in New York City have found a workaround. By adding extra “ghost” electrons in their computations that interact with the system’s actual electrons, they were able to simulate entanglement.

An international research team led by the Department of Microstructured Quantum Matter at the MPSD reports the first observation of switchable chiral transport in a structurally achiral crystal, the Kagome superconductor CsV₃Sb₅. Their work has been published in Nature.

Whether or not an object is indistinguishable from its mirror image has important consequences for its physical behavior. Say you watch a basketball player in a mirror. The ball, the player and their surroundings are, at first glance, just the same in the mirror as in real life. But if observed closely, some details are different. The ball in the player’s right hand now appears in their left hand in the mirror. While the mirror image still shows the same hand, it has clearly changed from a left to a right hand or vice versa. Many other physical objects also have mirror images that differ in a key aspect, just like hands, which is why scientists call them handed or chiral (from Greek χϵρι = hand). Others, like the ball, cannot be distinguished from their mirror image, which makes them achiral.

Chirality is one of the most fundamental geometric properties and plays a special role in biology, chemistry and physics. It can cause surprising effects: One version of the carvone molecule, for example, produces a spearmint smell but its chiral—mirrored—equivalent smells of caraway.

The best examples are simple. This is especially true in quantum computing, where complexity can get out of hand pretty fast. A team of researchers at D-Wave, with collaborators from USC, Tokyo Tech, and Saitama Medical University, recently explored a quantum phase transition — a complex subject by anyone’s standards — in a very simple 1D chain of magnetic spins. Our work, published today in Nature Physics, studies quantum critical dynamics in a coherently annealed Ising chain. Here are a few things we learned along the way.

Programmable quantum phase transitions, as ordered

Phase transitions, such as water to ice, are commonly attributed to changes in temperature. But there is another type of phase transition —-a quantum phase transition (QPT) —-where quantum effects determine the properties of a physical system, in the absence of thermal effects. In a 1D chain, spins at the end of the simulation are either “up” or “down”, and we get “kinks” separating blocks of up spins and down spins (during the simulation, spins can be in a superposition of up and down). The density and spacing of kinks depend on, among other things, the speed and “quantumness” of the experiment. In this work we guided the programmable system of spins through a QPT and investigated the effect of varying parameters such as speed, system size, and temperature.

Scientists have demonstrated a powerful technique that will allow quantum computers to store much more information in photons of light. The team managed to encode eight levels of data into photons and read it back easily, representing an exponential leap over previous systems.

Traditional computers store and process information in binary bits, which can hold a value of zero or one. Quantum computers boost this power drastically with their quantum bits, or qubits, which can hold values of zero, one or both at the same time. But an emerging version of qubits, known as qudits, up the game even more. Rather than just two values like qubits, qudits can theoretically contain dozens of different values, greatly increasing the data processing and storage potential. Better yet, qudits are also more resilient against external noise that can disrupt qubits.

But, of course, there’s a catch: it’s hard to measure and read back data stored on qudits. So for the new study, researchers at Oak Ridge National Laboratory, Purdue University and EPFL have developed a technique to produce and read qudits more reliably. In their experiments, they generated qudits that could each hold up to eight levels of information, and quantum-entangled them in pairs to generate a 64-dimensional quantum space. This, the team says, is four times larger than in previous studies.

Quantum science has not only deepened human understanding of the structure of matter and its microscopic interactions, but also introduced a new paradigm of computing and information science—quantum computing and quantum simulation. Quantum informatics research has won the 2022 Nobel Prize in Physics.

Among many quantum computing and simulation platforms, Rydberg Atom Arrays is considered the most promising system to show quantum superiority among many programmable quantum simulator platforms in recent years due to its largest number of qubits and highest experimental accuracy.

Such optical lattices consist of individual neutral alkaline-earth atoms with significant dipole moments trapped in arrays of microscopic dipole traps, which can be optically moved at will to make desired lattice geometry. Each atom can be excited to its Rydberg state, and a pair of excited states interact through their dipole moments via a long-range interaction.

One of the most successful theories of 20th century science is cosmic inflation, which preceded and set up the hot Big Bang. W e also know how quantum fields generally work, and if inflation is a quantum field (which we strongly suspect it is), then there will always be more “still-inflating” space out there. Whenever and wherever inflation ends, you get a hot Big Bang. If inflation and quantum field theory are both correct, a Multiverse is a must.

When we look out at the Universe today, it simultaneously tells us two stories about itself. One of those stories is written on the face of what the Universe looks like today, and includes the stars and galaxies we have, how they’re clustered and how they move, and what ingredients they’re made of. This is a relatively straightforward story, and one that we’ve learned simply by observing the Universe we see.

But the other story is how the Universe came to be the way it is today, and that’s a story that requires a little more work to uncover. Sure, we can look at objects at great distances, and that tells us what the Universe was like in the distant past: when the light that’s arriving today was first emitted. But we need to combine that with our theories of the Universe — the laws of physics within the framework of the Big Bang — to interpret what occurred in the past. When we do that, we see extraordinary evidence that our hot Big Bang was preceded and set up by a prior phase: cosmic inflation. But in order for inflation to give us a Universe consistent with what we observe, there’s an unsettling appendage that comes along for the ride: a multiverse. Here’s why physicists overwhelmingly claim that a multiverse must exist.

There are many ways to interpret quantum mechanics, each weirder than the last. Theoretical physicist Sean Carroll says that the most plausible is the Many-Worlds theory.

The idea that an infinite number of parallel worlds could exist alongside our own is hard to wrap the mind around, but a version of this so-called Many Worlds theory could provide an answer to the controversial idea of quantum mechanics and its many different interpretations.

Bill Poirier, a professor of physics at Texas Tech University in Lubbock, proposed a theory that not only assumes parallel worlds exist, but also says their interaction can explain all the quantum mechanics “weirdness” in the observable universe.