Volume 14 Issue 6, June 2018

Energy levels in superconducting quantum devices are highly sensitive to charge fluctuations. Generally, this is considered a bug, but new work transforms this sensitivity into the defining feature of a novel device.

It’s still unclear which problems can be solved by near-term quantum computers that are beyond the reach of their classical counterparts. A new analysis makes a practical assessment of how sampling the output of a quantum circuit leaves supercomputers in the dust.

Light can be coupled to sound via Brillouin scattering, but realizing an efficient interaction isn’t trivial. A new type of resonator succeeds in doing so in a macroscopic device — boasting features that better its nanoscale counterparts.

Cells change shape and volume when they divide — not a simple task, especially when they are confined by surrounding tissue. Experiments now reveal that hydrostatic pressure changes generate the pushing forces that cells need to create space for division.

The addition of nihonium, moscovium, tennessine and oganesson to the periodic table are a reminder of the achievements in nuclear physics and chemistry. Witold Nazarewicz outlines the future challenges for the field.

A technique allows optimal inference of the structure of a network when the available observed data are rich but noisy, incomplete or otherwise unreliable.

Deterministic entanglement of a superconducting qubit and an itinerant microwave photon followed by high-fidelity qubit readout realizes a quantum non-demolition measurement of a microwave photon.

Cavity polaritons whose matter component is composed of highly excited Rydberg atoms are shown to act as a zero-dimensional quantum dot. Trapping 150 polaritons led to the observation of blockaded photon transport.

Doppler-free, ultrahigh-resolution rotational spectroscopy is reported for small molecular ions in a linear quadrupole trap. With 10^–9 fractional linewidth, this method has a 50-fold improvement over previous reports.

Significant enhancement of carrier injection into the conduction band is observed for GaAs subjected to intense resonant near-infrared laser pumping. Attosecond-resolved investigation reveals the interplay between the intra- and interband transitions.

Erasing a bit of information has a fundamental, minimal energy cost that is given by the Landauer limit. The erasure of quantum information from a quantum-spin memory register encoded in a molecular nanomagnet is shown to obey the same principle.

The many phases of water ice continue to be fertile ground for surprising discoveries. This latest study reveals that ice II vanishes from the phase diagram of water upon the addition of small amounts of ammonium fluoride.

A quantity that connects quantum information and gravity in the light of gauge/gravity correspondence is pointed out, leading to interesting properties of the entanglement of purification predicted in the holographic theories.

Finding the relevant degrees of freedom of a system is a key step in any renormalization group procedure. But this can be difficult, particularly in strongly interacting systems. A machine-learning algorithm proves adept at identifying them for us.

Complex networks are not obviously renormalizable, as different length scales coexist. Embedding networks in a geometrical space allows the definition of a renormalization group that can be used to construct smaller-scale replicas of large networks.

The charge–phase duality in superconductors implies that the well-known SQUID has an analogue based on the interference of fluxons. Such a ‘charge quantum interference device’ (or CQUID) has now been experimentally demonstrated.

As a benchmark for the development of a future quantum computer, sampling from random quantum circuits is suggested as a task that will lead to quantum supremacy—a calculation that cannot be carried out classically.

Optomechanical coupling to macroscopic phonon modes of a bulk acoustic-wave resonator is demonstrated, providing access to high acoustics quality factors for phononic modes at high frequencies that are robust to decoherence.

A metamaterial-based acoustic sink has been designed to serve the purpose of absorbing the diverging waves and demonstrating three-dimensional sub-diffraction spherical sound wave focusing.

Epithelial cells are shown to scale via a shape distribution that is common to a number of different systems, suggesting that cell shape and shape variability are constrained through a relationship that is purely geometrical.

Little is known about how a cell’s surroundings within tissue influence the mechanics of its division. Experiments on constrained dividing cells reveal that they create protrusive forces in order to undergo the shape changes required for division.

Tests of one of the most fundamental theories in physics reveal an issue with the size of the proton — or the Rydberg constant. Thomas Udem explains.