Lifeboat Foundation

O.o! If the universe is some sorta hologram then this could be a clue to our actual reality.

Last December, the Nobel Prize in Physics was awarded for experimental evidence of a quantum phenomenon that has been known for more than 80 years: entanglement. As envisioned by Albert Einstein and his collaborators in 1935, quantum objects can be mysteriously correlated even when separated by great distances. But as strange as the phenomenon may seem, why is such an old idea still worthy of the most prestigious award in physics?

Coincidentally, just weeks before the new Nobel laureates were honored in Stockholm, another team of respected scientists from Harvard, MIT, Caltech, Fermilab and Google reported that they ran a process on Google’s quantum computer that could be interpreted as a wormhole. Wormholes are tunnels through the universe that can function as a shortcut through space and time and are loved by science fiction fans, and although the tunnel realized in this latest experiment only exists in a two-dimensional toy universe, it could be a breakthrough for the future represent research at the forefront of physics.

Continue reading “Why more and more physicists consider space and time to be ‘illusions’” »

Researchers have learned much about neutrinos over the past few decades, but some mysteries remain unsolved. For example, the standard model predicts that neutrinos are massless, but experiments say otherwise. One possible solution to this mass mystery involves another group of neutrinos that does not interact directly via the weak nuclear force and is therefore extremely difficult to detect. David Moore of Yale University and his colleagues have proposed a way to search for these so-called sterile neutrinos using a radioactive nanoparticle suspended in a laser beam [1].

Moore and his colleagues suggest levitating a 100-nm-diameter silica sphere in an optical trap and cooling it to its motional ground state. If the nanoparticle is filled with nuclei that decay by emitting neutrinos—such as certain argon or phosphorous isotopes—then electrons and neutrinos zipping from decaying nuclei should give it a momentum kick. By measuring the magnitude of this kick, the team hopes to determine the neutrinos’ momenta. Although most of these neutrinos will be the familiar three neutrino flavors, sterile neutrinos—if they exist—should also occasionally be emitted, producing unexpectedly small momentum kicks. Moore says that monitoring a single nanoparticle for one month would equate to a sterile-neutrino sensitivity 10 times better than that of any experiment tried so far.

Moore and his team are currently working on a proof-of-principle experiment using alpha-emitting by-products of radon, which result in a larger momentum kick. Once the techniques are optimized, they expect that switching to beta-decaying isotopes will let them see heavy sterile neutrinos in the 0.1–1 MeV mass range. Introducing more quantum tricks to manipulate the nanoparticle’s quantum state will make future experiments sensitive to even lighter sterile neutrinos.

Researchers from the University of Sussex and Universal Quantum have demonstrated for the first time that quantum bits (qubits) can directly transfer between quantum computer microchips and demonstrated this with record-breaking speed and accuracy. This breakthrough resolves a major challenge in building quantum computers large and powerful enough to tackle complex problems that are of critical importance to society.

Today, quantum computers operate on the 100-qubit scale. Experts anticipate millions of qubits are required to solve important problems that are out of reach of today’s most powerful supercomputers. There is a global quantum race to develop quantum computers that can help in many important societal challenges from drug discovery to making fertilizer production more energy efficient and solving important problems in nearly every industry, ranging from aeronautics to the financial sector.

In the research paper, published today in Nature Communications, the scientists demonstrate how they have used a new and powerful technique, which they dub “UQ Connect,” to use electric field links to enable qubits to move from one quantum computing microchip module to another with unprecedented speed and precision. This allows chips to slot together like a jigsaw puzzle to make a more powerful quantum computer.

A new design for an optical fiber borrows concepts from topology to protect light from imperfections in the fiber’s light-guiding materials or from distortions in its cross section.

Using concepts from the mathematical field of topology, researchers at the University of Bath, UK, have designed an optical fiber that can robustly propagate light, even if there are variations in the properties of its light-guiding materials or in its overall geometry [1]. The team thinks that this newfound topological protection could enable advances in optical communication and photonic quantum computing.

The concept of topology is often explained using a joke about a donut and a coffee cup. A coffee cup made of rubber can be continuously twisted and stretched—no cuts need to be made—so that it takes on the shape of a donut. Even though the object’s outline changes under this transformation, its essence remains the same—it contains one hole. Thus, the quip goes, a topologist cannot tell the difference between the two things.

Researchers have achieved long-distance entanglement between two calcium ions, each of which lies in a different building, showing that trapped ions could be used to create quantum networks.

Among the many candidate platforms for quantum-information applications, trapped-ion qubits are promising because of their long coherence times and their potential for multiqubit operations (see Viewpoint: Trapped Ions Make Impeccable Qubits). Alone, those properties are insufficient for some quantum applications, however: to build quantum communication networks, for example, requires the qubits’ delicate quantum states be shared over long distances. Demonstrations of this ability have been lacking for trapped-ion systems. Now a team led by Benjamin Lanyon at the Institute for Quantum Optics and Quantum Information, Austria, and Tracy Northup at the University of Innsbruck, Austria, have addressed this shortfall by entangling two trapped-ion qubits residing in different buildings [1].

Lanyon, Northup, and colleagues used trapped-ion qubits inside optical cavities. For each qubit, they excited the ion using a dual-wavelength laser, prompting the ion to emit a single photon. The photon’s polarization depended on which of the two laser wavelengths the ion absorbed, entangling the photon with the ion’s final state. To entangle the two ions, the team then transmitted the photon from one ion through 510 m of optical fiber to a beam splitter near the other ion, where the two photons interacted. The researchers claimed successful entanglement when they subsequently detected a pair of photons with specific individual polarizations.

Quantum sensing represents one of the most promising applications of quantum technologies, with the aim of using quantum resources to improve measurement sensitivity. In particular, sensing of optical phases is one of the most investigated problems, considered key to developing mass-produced technological devices.

Optimal usage of quantum sensors requires regular characterization and calibration. In general, such calibration is an extremely complex and resource-intensive task—especially when considering systems for estimating multiple parameters, due to the sheer volume of required measurements as well as the computational time needed to analyze those measurements. Machine-learning algorithms present a powerful tool to address that complexity. The discovery of suitable protocols for algorithm usage is vital for the development of sensors for precise quantum-enhanced measurements.

A particular type of machine-learning algorithm known as “reinforcement learning” (RL) relies on an intelligent agent guided by rewards: Depending on the rewards it receives, it learns to perform the right actions to achieve the desired optimization. The first experimental realizations using RL algorithms for the optimization of quantum problems have been reported only very recently. Most of them still rely on prior knowledge of the model describing the system. What is desirable is instead a completely model-free approach, which is possible when the agent’s reward does not depend on the explicit system model.

Quantum simulations of the hydroxide anion and hydroxyl radical are reported, employing variational quantum algorithms for near-term quantum devices. The energy of each species is calculated along the dissociation curve, to obtain information about the stability of the molecular species being investigated. It is shown that simulations restricted to valence spaces incorrectly predict the hydroxyl radical to be more stable than the hydroxide anion. Inclusion of dynamical electron correlation from nonvalence orbitals is demonstrated, through the integration of the variational quantum eigensolver and quantum subspace expansion methods in the workflow of N-electron valence perturbation theory, and shown to correctly predict the hydroxide anion to be more stable than the hydroxyl radical, provided that basis sets with diffuse orbitals are also employed.

Individual atoms trapped by optical ‘tweezers’ are emerging as a promising computational platform.

This life of yours which you are living is not merely a piece of the entire existence, but is in a certain sense the whole.