Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: quantum physics – Page 46

A recent study in Physical Review Letters explores quantum effects on black hole thermodynamics and geometry, focusing on extending two classical inequalities into the quantum regime.

Black holes have been thoroughly studied through a classical approach based on Einstein’s general theory of relativity. However, this approach does not account for quantum effects like Hawking radiation.

The goal of the study was for the researchers to refine classical theories by including quantum effects, thereby offering an improved understanding of black hole dynamics.

Read more | >

MIT physicists have taken a key step toward solving the puzzle of what leads electrons to split into fractions of themselves. Their solution sheds light on the conditions that give rise to exotic electronic states in graphene and other two-dimensional systems.

The new work is an effort to make sense of a discovery that was reported earlier this year by a different group of physicists at MIT, led by Assistant Professor Long Ju. Ju’s team found that electrons appear to exhibit “fractional charge” in pentalayer graphene — a configuration of five graphene layers that are stacked atop a similarly structured sheet of boron nitride.

Ju discovered that when he sent an electric current through the pentalayer structure, the electrons seemed to pass through as fractions of their total charge, even in the absence of a magnetic field. Scientists had already shown that electrons can split into fractions under a very strong magnetic field, in what is known as the fractional quantum Hall effect. Ju’s work was the first to find that this effect was possible in graphene without a magnetic field — which until recently was not expected to exhibit such an effect.

Read more | >

“Quantum physicists are realizing that they can’t ignore the fact that the reference frame Alice is anchored to … might have multiple possible locations at once.”

The quantum nature of reference frames can even affect the perceived order of events.

In a paper this year, the physicist Časlav…

The reference frames from which observers view quantum events can themselves have multiple possible locations at once — an insight with potentially major ramifications.

Continue reading “In the Quantum World, Even Points of View Are Uncertain” | >

The rise of quantum computing is more than a technological advancement; it marks a profound shift in the world of cybersecurity, especially when considering the actions of state-sponsored cyber actors. Quantum technology has the power to upend the very foundations of digital security, promising to dismantle current encryption standards, enhance offensive capabilities, and recalibrate the balance of cyber power globally. As leading nations like China, Russia, and others intensify their investments in quantum research, the potential repercussions for cybersecurity and international relations are becoming alarmingly clear.

Imagine a world where encrypted communications, long thought to be secure, could be broken in mere seconds. Today, encryption standards such as RSA or ECC rely on complex mathematical problems that would take traditional computers thousands of years to solve. Quantum computing, however, changes this equation. Using quantum algorithms like Shor’s, a sufficiently powerful quantum computer could factorize these massive numbers, effectively rendering these encryption methods obsolete.

This capability could give state actors the ability to decrypt communications, access sensitive governmental data, and breach secure systems in real time, transforming cyber espionage. Instead of months spent infiltrating networks and monitoring data flow, quantum computing could provide immediate access to critical information, bypassing traditional defenses entirely.

Read more | >

Strong interactions between subatomic particles like electrons occur when they are at a specific energy level known as the van Hove singularity. These interactions give rise to unusual properties in quantum materials, such as superconductivity at high temperatures, potentially ushering in exciting technologies of tomorrow.

Research suggests that allow electrons to flow only on their surface to be promising . However, the quantum properties of these materials remain relatively unexplored.

A study co-led by Nanyang Asst Prof Chang Guoqing of NTU’s School of Physical and Mathematical Sciences identified two types of van Hove singularities in the topological materials rhodium monosilicide (RhSi) and cobalt monosilicide (CoSi).

Read more | >

Achieving the full potential of quantum computing will require the development of quantum gates—circuits that carry out fundamental operations—with much higher fidelity than is currently available. An average gate fidelity surpassing 99.9%, for example, would enable not only efficient fault-tolerant quantum computing with error correction but also effective mitigation of errors in current noisy intermediate-scale quantum devices. In this work, we report on a two-qubit gate that achieves that milestone and sustains it for 12 h.

Superconducting qubits, with their ease of scalability and controllability, are prime candidates for building quantum processors. One type known as a transmon is renowned for its high coherence and ease of manufacturing and is thus already widely embraced in academia and industry. In general, single-qubit gates need negligible coupling between two transmon qubits, whereas two-qubit gates require a large coupling. This necessitates a coupling mechanism that can be tuned to both nearly zero and a very large value.

Various coupling schemes based on transmons have been shown to address this issue. Our work focuses on an innovative coupler known as the double-transmon coupler (DTC), which has been only theoretically proposed. We report the first experimental realization of the DTC, achieving gate fidelities of 99.9% for two-qubit gates and 99.98% for single-qubit gates, demonstrated by using two transmons coupled by the DTC.

Read more | >

Unitary collapse of Schrödinger’s cat state https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.L030202

Schrödinger’s cat, that iconic thought experiment where a cat in a box is both alive and dead until someone peeks.

The authors study a system composed of a single qubit coupled to a soft-mode quantum oscillator. They show that spontaneous unitary evolution of this system create a Schr\ odinger-cat-like state of the oscillator, which is subsequently lost in a sudden process strongly resembling the measurement-induced collapse of wave function.

Read more | >

The identification of a new type of symmetry in statistical mechanics could help scientists derive and interpret fundamental relationships in this branch of physics.

Symmetry is a foundational concept in physics, describing properties that remain unchanged under transformations such as rotation and translation. Recognizing these invariances, whether intuitively or through complex mathematics, has been pivotal in developing classical mechanics, the theory of relativity, and quantum mechanics. For example, the celebrated standard model of particle physics is built on such symmetry principles. Now Matthias Schmidt and colleagues at the University of Bayreuth, Germany, have identified a new type of invariance in statistical mechanics (the theoretical framework that connects the collective behavior of particles to their microscopic interactions) [1]. With this discovery, the researchers offer a unifying perspective on subtle relationships between observable properties and provide a general approach for deriving new relations.

The concept of conserved, or time-invariant, properties has roots in ancient philosophy and was crucial to the rise of modern science in the 17th century. Energy conservation became a cornerstone of thermodynamics in the 19th century, when engineers uncovered the link between heat and work. Another important type of invariance is Galilean invariance, which states that the laws of physics are identical in all reference frames moving at a constant velocity relative to each other, resulting in specific relations between positions and velocities in different frames. Its extension, Lorentz invariance, posits that the speed of light is independent of the reference frame. Einstein’s special relativity is based on Lorentz invariance, while his general relativity broadens the idea to all coordinate transformations. These final examples illustrate that invariance not only provides relations between physical observables but can shape our understanding of space, time, and other basic concepts.

Read more | >

Researchers at Rice University have found a new way to improve a key element of thermophotovoltaic (TPV) systems, which convert heat into electricity via light. Using an unconventional approach inspired by quantum physics, Rice engineer Gururaj Naik and his team have designed a thermal emitter that can deliver high efficiencies within practical design parameters.

The research could inform the development of thermal-energy electrical storage, which holds promise as an affordable, grid-scale alternative to batteries. More broadly, efficient TPV technologies could facilitate renewable energy growth—an essential component of the transition to a net-zero world. Another major benefit of better TPV systems is recouping from industrial processes, making them more sustainable. To put this in context, up to 20–50% of the heat used to transform raw materials into consumer goods ends up being wasted, costing the United States economy over $200 billion annually.

TPV systems involve two main components: photovoltaic (PV) cells that convert light into electricity and thermal emitters that turn heat into light. Both of these components have to work well in order for the system to be efficient, but efforts to optimize them have focused more on the PV cell.

Read more | >

In an era where AI and data are driving the scientific revolution, quantum computing technology is emerging as another game-changer in the development of new drugs and new materials.

Dr. Hyang-Tag Lim’s research team at the Center for Quantum Technology at the Korea Institute of Science and Technology (KIST) has implemented a quantum computing algorithm that can estimate interatomic bond distances and ground state energies with chemical accuracy using fewer resources than conventional methods, and has succeeded in performing accurate calculations without the need for additional quantum error mitigation techniques.

The work is published in the journal Science Advances.

Read more | >