Lifeboat Foundation

We study the question of how to decompose Hilbert space into a preferred tensor-product factorization without any pre-existing structure other than a Hamiltonian operator, in particular the case of a bipartite decomposition into “system” and “environment.” Such a decomposition can be defined by looking for subsystems that exhibit quasi-classical behavior. The correct decomposition is one in which pointer states of the system are relatively robust against environmental monitoring (their entanglement with the environment does not continually and dramatically increase) and remain localized around approximately-classical trajectories. We present an in-principle algorithm for finding such a decomposition by minimizing a combination of entanglement growth and internal spreading of the system. Both of these properties are related to locality in different ways.

When I first started looking into quantum computing I had a fairly pessimistic view about its near-term commercial prospects, but I’ve come to think we’re only a few years away from seeing serious returns on the technology.

ab initio calculations

Classical computing is of very little help when the task to be accomplished pertains to ab initio calculations. With quantum computing in place, you have a quantum system simulating another quantum system. Furthermore, tasks such as modelling atomic bonding or estimating electron orbital overlaps can be done much more precisely.

►Is faster-than-light (FTL) travel possible? In most discussions of this, we get hung up on the physics of particular ideas, such as wormholes or warp drives. But today, we take a more zoomed out approach that addresses all FTL propulsion — as well as FTL messaging. Because it turns out that they all allow for time travel. Join us today as we explore why this is so and the profound consequences that ensue. Special thanks to Prof Matt.

Written & presented by Prof David Kipping. Special thanks to Prof Matt Buckley for fact checking and his great blog article that inspired this video (http://www.physicsmatt.com/blog/2016/8/25/why-ftl-implies-time-travel)

Continue reading “Why Going Faster-Than-Light Leads to Time Paradoxes” »

A new method of identifying gravitational wave signals using quantum computing could provide a valuable new tool for future astrophysicists.

A team from the University of Glasgow’s School of Physics & Astronomy have developed a quantum algorithm to drastically cut down the time it takes to match gravitational wave signals against a vast databank of templates.

This process, known as matched filtering, is part of the methodology that underpins some of the gravitational wave signal discoveries from detectors like the Laser Interferometer Gravitational Observatory (LIGO) in America and Virgo in Italy.

In the new field of quantum computing, magnetic interactions could play a role in relaying quantum information.

In new research, Argonne scientists achieved efficient quantum coupling between two distant magnetic devices, which which may be useful for creating new quantum information technology devices — https://bit.ly/3uk88Q3

What do quantum computers have to do with smog-filled London streets, flying submarines, waistcoats, petticoats, Sherlock Holmesian mysteries, and brass goggles?

A whole lot, according to Nicole Yunger Halpern. Last week, the theoretical physicist joined Jacob Barandes, co-director of graduate studies for physics, to discuss her new book, “Quantum Steampunk: The Physics of Yesterday’s Tomorrow.” In it, Yunger Halpern dissects a new branch of science—quantum thermodynamics, or quantum steampunk as she calls it—by fusing steampunk fiction with nonfiction and Victorian-era thermodynamics (the heat and energy that gets steam engines pumping) with quantum physics. Yunger Halpern presents a whimsical lens through which readers can watch a “scientific revolution that’s happening in real time,” Barandes said, exploring mysteries even Holmes couldn’t hope to solve, such as why time flows in only one direction.

“This fusion of old and new creates a wonderful sense of nostalgia and adventure, romance and exploration,” Yunger Halpern said during a virtual Harvard Science Book Talk presented by the University’s Division of Science, Cabot Science Library, and Harvard Book Store. In steampunk, she continued, “fans dress up in costumes full of top hats and goggles and gears and gather at conventions. What they dream, I have the immense privilege of having the opportunity to live.”

A new theoretical paper has tackled the phenomenon of quantum decoherence.

A new theoretical paper has tackled the phenomenon of quantum decoherence, the process by which objects slip out of the quantum world and start behaving classically. The paper approaches this in a new way by applying an effect of general relativity to decoherence. The paper claims that gravity is the key to the disparity between the weird quantum world and the everyday, familiar world of human-sized objects in which we live.

Schrödinger’s cat is an example of a quantum system which might decohere due to time dilation — and myriad other interactions.

Quantum information theory: Quantum complexity grows linearly for an exponentially long time.

Physicists know about the huge chasm between quantum physics and the theory of gravity. However, in recent decades, theoretical physics has provided some plausible conjecture to bridge this gap and to describe the behavior of complex quantum many-body systems, for example black holes and wormholes in the universe. Now, a theory group at Freie Universität Berlin and HZB, together with Harvard University, USA, has proven a mathematical conjecture about the behavior of complexity in such systems, increasing the viability of this bridge. The work is published in Nature Physics.

“We have found a surprisingly simple solution to an important problem in physics,” says Prof. Jens Eisert, a theoretical physicist at Freie Universität Berlin and HZB. “Our results provide a solid basis for understanding the physical properties of chaotic quantum systems, from black holes to complex many-body systems,” Eisert adds.