How to Win a Nobel Prize

In the last 30 years there have been no big breakthroughs in our knowledge of physics and the world that we live in. Despite the media attention surrounding the detection of Gravitational Waves, the exposure of the Higgs Boson at CERN and the Hubble space telescope evidence for the expansion of the universe twenty years earlier, all of these discoveries were merely confirmations of predictions that had been mainstream scientific…

Read More…

First Support for a Physics Theory of Life

Take chemistry, add energy, get life. The first tests of Jeremy England’s provocative origin-of-life hypothesis are in, and they appear to show how order can arise from nothing. …

Read More...

Comments Off on First Support for a Physics Theory of Life

Building Codes for Bacterial Cities

Hydrodynamics and competition guide the architectural design of biofilm fortresses. …

Read More...

Comments Off on Building Codes for Bacterial Cities

The Beautiful Mathematical Explorations of Maryam Mirzakhani

After her untimely death, Maryam Mirzakhani’s life is best remembered through her work. …

Read More...

Comments Off on The Beautiful Mathematical Explorations of Maryam Mirzakhani

Fast time-domain measurements on telecom single photons

Direct measurements on the temporal envelope of quantum light are a challenging task and not many examples are known because most classical pulse characterisation methods do not work on the single-photon level. Knowledge of both spectrum and timing can, however, give insights on properties that cannot be determined by the spectral intensity alone. While temporal measurements on single photons on timescales of tens of picoseconds are possible with superconducting photon detectors, and picosecond measurements have been performed using streak cameras, there are no commercial single-photon sensitive devices with femtosecond resolution available. While time-domain sampling using sum-frequency generation has already been exploited for such a measurement, inefficient conversion has necessitated long integration times to build the temporal profile. We demonstrate a highly efficient waveguided sum-frequency generation process in Lithium Niobate to measure the temporal envelope of single … …

Read More...

Comments Off on Fast time-domain measurements on telecom single photons

Theory of phase-mixing amplification in an optomechanical system

The investigation of the ultimate limits imposed by quantum mechanics on amplification represents an important topic both on a fundamental level and from the perspective of potential applications. We discuss here a novel regime for bosonic linear amplifiers—beside phase-insensitive and phase-sensitive amplification—which we term here phase-mixing amplification. Furthermore, we show that phase-mixing amplification can be realised in a cavity optomechanical setup, constituted by a mechanical resonator which is dispersively coupled to an optomechanical cavity asymmetrically driven around both mechanical sidebands. While, in general, this amplifier is phase-mixing, for a suitable choice of parameters, the amplifier proposed here operates as a phase-sensitive amplifier. We show that both configurations allow amplification with an added noise below the quantum limit of (phase-insensitive) amplification in a parameter range compatible with current experiments in microwave circuit optom… …

Read More...

Comments Off on Theory of phase-mixing amplification in an optomechanical system

How many atoms get excited when they decay?

We analyse the time evolution of a two-level system prepared in a superposition of its ground state and radiatively unstable excited state. We show that by choosing appropriate means of detection of the radiated field, we can steer the evolution of the emitter and herald its preparation in the fully excited state. We determine the probability for the occurrence of this ‘excitation during the decay’ of a remote emitter. …

Read More...

Comments Off on How many atoms get excited when they decay?

The pitfalls of planar spin-glass benchmarks: raising the bar for quantum annealers (again)

In an effort to overcome the limitations of random spin-glass benchmarks for quantum annealers, focus has shifted to carefully crafted gadget-based problems whose logical structure typically has a planar topology. Recent experiments on these gadget problems using a commercially available quantum annealer have demonstrated an impressive performance over a selection of commonly used classical optimisation heuristics. Here, we show that efficient classical optimisation techniques, such as minimum-weight-perfect matching, can solve these gadget problems exactly and in polynomial time. We present approaches on how to mitigate this shortcoming of commonly used benchmark problems based on planar logical topologies. …

Read More...

Comments Off on The pitfalls of planar spin-glass benchmarks: raising the bar for quantum annealers (again)