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Random circuits have no shortcuts

Nature Physics - Mon, 28/03/2022 - 00:00

Nature Physics, Published online: 28 March 2022; doi:10.1038/s41567-022-01559-2

Theoretical physicists studying black holes have produced a conjecture that random quantum circuits cannot be simplified. Now, a minimal version of this conjecture has been proven, reaching a milestone in quantum-circuit complexity theory.

Linear growth of quantum circuit complexity

Nature Physics - Mon, 28/03/2022 - 00:00

Nature Physics, Published online: 28 March 2022; doi:10.1038/s41567-022-01539-6

The dynamics of quantum states underlies the emergence of thermodynamics and even recent theories of quantum gravity. Now it has been proven that the quantum complexity of states evolving under random operations grows linearly in time.

Manipulation of Dirac band curvature and momentum-dependent <i>g</i> factor in a kagome magnet

Nature Physics - Mon, 28/03/2022 - 00:00

Nature Physics, Published online: 28 March 2022; doi:10.1038/s41567-022-01558-3

The change in a band structure when a magnetic field is applied should depend on the momentum of the electronic state, but this is hard to measure. Now, this effect is demonstrated in a topological magnet.

Inverse Occam’s razor

Nature Physics - Mon, 28/03/2022 - 00:00

Nature Physics, Published online: 28 March 2022; doi:10.1038/s41567-022-01575-2

Scientists have long preferred the simplest possible explanation of their data. More recently, a worrying trend to favour unnecessarily complex interpretations has taken hold.

A spotlight on circular states

Nature Physics - Thu, 24/03/2022 - 00:00

Nature Physics, Published online: 24 March 2022; doi:10.1038/s41567-022-01572-5

Circular Rydberg states provide an ideal resource for large-scale quantum computing and simulation. These circular states can be controlled using coherent optical pulses, providing a route to programmable quantum hardware.

Non-specific adhesive forces between filaments and membraneless organelles

Nature Physics - Thu, 24/03/2022 - 00:00

Nature Physics, Published online: 24 March 2022; doi:10.1038/s41567-022-01537-8

Many organelles in the cell are not encapsulated in a membrane—they are liquid-like domains formed through phase separation. The liquid-like nature of such domains leads to adhesive interactions between the cytoskeleton filaments and organelles.

Simulation of open quantum systems by automated compression of arbitrary environments

Nature Physics - Thu, 24/03/2022 - 00:00

Nature Physics, Published online: 24 March 2022; doi:10.1038/s41567-022-01544-9

It is difficult to analyse open quantum systems because an accurate description of their environments becomes intractably large. A method that automatically identifies an efficient representation provides a flexible approach to numerical simulations.

Optical coherent manipulation of alkaline-earth circular Rydberg states

Nature Physics - Thu, 24/03/2022 - 00:00

Nature Physics, Published online: 24 March 2022; doi:10.1038/s41567-022-01519-w

The capabilities of optically accessible Rydberg levels are limited by their lifetime. An experiment demonstrates how to detect and manipulate long-lived circular states through the coupling of valence electrons in alkaline-earth Rydberg atoms.

Disentangling high-order mechanisms and high-order behaviours in complex systems

Nature Physics - Mon, 21/03/2022 - 00:00

Nature Physics, Published online: 21 March 2022; doi:10.1038/s41567-022-01548-5

Disentangling high-order mechanisms and high-order behaviours in complex systems

Collision detection with logic

Nature Physics - Mon, 21/03/2022 - 00:00

Nature Physics, Published online: 21 March 2022; doi:10.1038/s41567-022-01550-x

Controlling chemistry at the single-collision level is one of the main goals of experiments at ultralow temperatures. A method based on quantum logic techniques has now been shown to detect inelastic collisions in a hybrid ion–atom platform.

Quantum logic detection of collisions between single atom–ion pairs

Nature Physics - Mon, 21/03/2022 - 00:00

Nature Physics, Published online: 21 March 2022; doi:10.1038/s41567-022-01517-y

The study of single-atom collisions in ultracold gases has so far been limited to certain atomic and molecular species. A more general scheme based on quantum logic techniques has now been realized in a hybrid cold ion–atom platform.

Discrete symmetry breaking defines the Mott quartic fixed point

Nature Physics - Mon, 21/03/2022 - 00:00

Nature Physics, Published online: 21 March 2022; doi:10.1038/s41567-022-01529-8

The Mott metal-to-insulator transition plays a key role in theoretical studies of high-temperature superconductors. A mathematical analysis of the theory of metals identifies a renormalization-group fixed point describing Mott physics.

Particle–hole asymmetric superconducting coherence peaks in overdoped cuprates

Nature Physics - Mon, 21/03/2022 - 00:00

Nature Physics, Published online: 21 March 2022; doi:10.1038/s41567-022-01534-x

Cuprates that are doped beyond the point that optimizes the critical temperature were thought to be understood. Now, a careful real-space investigation shows unconventional behaviour in the superconducting state caused by pair-breaking scattering.

Band transport by large Fröhlich polarons in MXenes

Nature Physics - Mon, 21/03/2022 - 00:00

Nature Physics, Published online: 21 March 2022; doi:10.1038/s41567-022-01541-y

The charge transport mechanism in MXenes—an emerging class of layered materials—is not yet fully understood. A combination of terahertz spectroscopy and transport measurements shows that the formation of large polarons play a crucial role.

A wing explained

Nature Physics - Thu, 17/03/2022 - 00:00

Nature Physics, Published online: 17 March 2022; doi:10.1038/s41567-022-01553-8

The origin of a well-known feature in relaxation data seen in many glass-forming materials has now — possibly — been resolved by means of computer simulations.

Mist and replication

Nature Physics - Thu, 17/03/2022 - 00:00

Nature Physics, Published online: 17 March 2022; doi:10.1038/s41567-022-01549-4

The transition from chemistry to evolvable molecular systems is at the core of origins of life studies. Now, the acidic dew–liquid water dynamic cycling inside simulated Hadean rock pores is found to possibly provide a confined environment for strand separation, replication, mutation, and the evolution of nucleic acids.

Direct observation of a dynamical glass transition in a nanomagnetic artificial Hopfield network

Nature Physics - Thu, 17/03/2022 - 00:00

Nature Physics, Published online: 17 March 2022; doi:10.1038/s41567-022-01538-7

A spin glass is a disordered system with randomized competing magnetic interactions. Now, a metamaterial artificial spin glass based on nanomagnets is reported, with rudimentary features of a neural network.

Relationships between structure, memory and flow in sheared disordered materials

Nature Physics - Thu, 17/03/2022 - 00:00

Nature Physics, Published online: 17 March 2022; doi:10.1038/s41567-022-01536-9

Whether and when a material deforms elastically or plastically depends on its microstructure. Experiments on two-dimensional colloidal systems show that in disordered materials, packing density, stress and a microstructure-related entropy govern deformations.

Microscopic origin of excess wings in relaxation spectra of supercooled liquids

Nature Physics - Thu, 17/03/2022 - 00:00

Nature Physics, Published online: 17 March 2022; doi:10.1038/s41567-022-01508-z

The dynamic relaxation spectrum of a supercooled liquid is asymmetric near the glass transition. Overcoming the difficulty of accessing low temperatures and long timescales, simulations now attribute this feature to dynamic facilitation.

Water cycles in a Hadean CO<sub>2</sub> atmosphere drive the evolution of long DNA

Nature Physics - Thu, 17/03/2022 - 00:00

Nature Physics, Published online: 17 March 2022; doi:10.1038/s41567-022-01516-z

Detailed microfluidics experiments and numerical simulations are used to analyse the role played by dew in the origin of life, and demonstrate that it can drive the first stages of Darwinian evolution for DNA and RNA.

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University of Crete - Department of Physics  - Voutes University Campus - GR-70013 Heraklion, Greece
phone: +30 2810 394300 - email: chair@physics.uoc.gr