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Category: quantum physics – Page 405

Nonclassical Advantage in Metrology Established via Quantum Simulations of Hypothetical Closed Timelike Curves

We construct a metrology experiment in which the metrologist can sometimes amend the input state by simulating a closed timelike curve, a worldline that travels backward in time. The existence of closed timelike curves is hypothetical. Nevertheless, they can be simulated probabilistically by quantum-teleportation circuits. We leverage such simulations to pinpoint a counterintuitive nonclassical advantage achievable with entanglement. Our experiment echoes a common information-processing task: A metrologist must prepare probes to input into an unknown quantum interaction. The goal is to infer as much information per probe as possible. If the input is optimal, the information gained per probe can exceed any value achievable classically. The problem is that, only after the interaction does the metrologist learn which input would have been optimal.

Physicists create new form of antenna for radio waves

University of Otago physicists have used a small glass bulb containing an atomic vapor to demonstrate a new form of antenna for radio waves. The bulb was “wired up” with laser beams and could therefore be placed far from any receiver electronics.

Dr. Susi Otto, from the Dodd-Walls Center for Photonic and Quantum Technologies, led the field testing of the portable atomic radio sensor. A paper on the creation was published in Applied Physics Letters.

Such sensors, that are enabled by atoms in a so-called Rydberg state, can provide superior performance over current antenna technologies as they are highly sensitive, have broad tunability, and small physical size, making them attractive for use in defense and communications.

The A.I. Dilemma

Tristan Harris and Aza Raskin discuss how existing A.I. capabilities already pose catastrophic risks to a functional society, how A.I. companies are caught in a race to deploy as quickly as possible without adequate safety measures, and what it would mean to upgrade our institutions to a post-A.I. world.

This presentation is from a private gathering in San Francisco on March 9th, 2023 with leading technologists and decision-makers with the ability to influence the future of large-language model A.I.s. This presentation was given before the launch of GPT-4.

We encourage viewers to consider calling their political representatives to advocate for holding hearings on AI risk and creating adequate guardrails.

For the podcast version, please visit: https://www.humanetech.com/podcast/the-ai-dilemma.

Continue reading “The A.I. Dilemma” | >

The four types of planetary civilizations, explained by Michio Kaku

Humanity is a type 0 civilization. Here’s what types 1, 2, and 3 look like, according to physicist Michio Kaku.

Is anybody out there? Renowned physicist Michio Kaku discusses we could identify and categorize advanced extraterrestrial civilizations.

According to Kaku, while recognizing intelligence in space is challenging, Quantum computers may be able to help sift through data for signals of intelligence, similarly to how we analyze patterns in dolphin communication.

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Solving quantum mysteries: New insights into 2D semiconductor physics

Researchers from Monash University have unlocked fresh insights into the behavior of quantum impurities within materials.

The new, international theoretical study introduces a novel approach known as the “quantum virial expansion,” offering a powerful tool to uncover the complex quantum interactions in two-dimensional semiconductors.

This breakthrough holds potential to reshape our understanding of complex quantum systems and unlock exciting future applications utilizing novel 2D materials.

Thought experiments and conservation laws: Reevaluating quantum conservation principles

Conservation laws are central to our understanding of the universe, and now scientists have expanded our understanding of these laws in quantum mechanics.

A conservation law in physics describes the preservation of certain quantities or properties in isolated physical systems over time, such as mass-energy, momentum, and electric charge.

Conservation laws are fundamental to our understanding of the universe because they define the processes that can or cannot occur in nature. For example, the conservation of momentum reveals that within a closed system, the sum of all momenta remains unchanged before and after an event, such as a collision.

There might be just one multiverse

The idea of the multiverse has at least two conceptually distinct sources in theoretical physics: quantum mechanics and cosmology. The many worlds of quantum mechanics are very different in terms of their nature and origin from cosmology’s multiverse. However, physicists have reason to believe that ultimately, these two distinct multiverses are in fact one and the same, writes David Wallace.

In big budget science-fiction and fantasy franchises, the “multiverse” is a collection of universes – some quite like our own, some differing from ours only in the way some historical event played out or some person’s life unfolded, some vastly different and filled with strange wonders. But in the drier and more disciplined world of modern physics, “multiverse” means… well, pretty much the same, only without the prospect of easily moving from one universe to the next. The multiverse of physics is revealed more subtly, by hints hidden in our observations and our theories.

Or rather: the multiverses of physics are revealed more subtly. For remarkably, physics gives us not one but three different multiverses, and reasons to accept all three.

Manipulating nonlinear exciton polaritons in a WS2 monolayer with artificial lattices

Exciton polaritons, hybrid quasiparticles caused by the strong exciton-photon coupling, constitute a unique prototype for studying many-body physics and quantum photonic phenomena traditionally in cryogenic conditions.

Atomically thin transition-metal dichalcogenides (TMDs), as exceptional semiconductors with room-temperature operations, have received much attention due to their fascinating valleytronics features and strong exciton resonance. Nevertheless, in TMDs microcavities, the overall nonlinear interaction strength of polaritons can be insignificant compared to that of other wide-bandgap semiconductors.

Considerable effort has been devoted to improving the nonlinear interactions, for instance, by resorting to 2s states, trion, and moiré or dipolar excitons. However, these excitons quickly dissipate at elevated temperatures and then destroy the strong coupling condition. Thus, achieving an appropriate combination of strong nonlinearity together with the thermal stability of the TMDs polaritons is highly sought after for realistic polariton-based integrated devices.

A quantum algorithm for the segmentation of a moving target in grayscale videos

Computer vision algorithms have become increasingly advanced over the past decades, enabling the development of sophisticated technologies to monitor specific environments, detect objects of interest in video footage and uncover suspicious activities in CCTV recordings. Some of these algorithms are specifically designed to detect and isolate moving objects or people of interest in a video, a task known as moving target segmentation.

While some conventional algorithms for moving target segmentation attained promising results, most of them perform poorly in real-time (i.e., when analyzing videos that are not pre-recorded but are being captured in the present moment). Some research teams have thus been trying to tackle this problem using alternative types of algorithms, such as so-called quantum algorithms.

Researchers at Nanjing University of Information Science and Technology and Southeast University in China recently developed a new quantum for the segmentation of moving targets in grayscale videos. This algorithm, published in Advanced Quantum Technologies, was found to outperform classical approaches in tasks that involve the analysis of in real-time.

Quantum Crafting: Atom-by-Atom Construction of a New Qubit Platform

Scientists at the IBS Center for Quantum Nanoscience (QNS) at Ewha Womans University have accomplished a groundbreaking step forward in quantum information science. In partnership with teams from Japan, Spain, and the US, they created a novel electron-spin qubit platform, assembled atom.

An atom is the smallest component of an element. It is made up of protons and neutrons within the nucleus, and electrons circling the nucleus.

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