quantum mechanics tagged posts

Researchers at Delft University of Technology have created a quantum circuit that enables them to listen to the weakest radio signal allowed by quantum mechanics. This new quantum circuit opens the door to possible future applications in areas such as radio astronomy and medicine (MRI). It also enables researchers to do experiments that can shed light on the interplay between quantum mechanics and gravity.

We have all been annoyed by weak radio signals at some point in our lives: our favourite song in the car turning to noise, being too far away from our wifi router to check our email...

The wavelength of emitted light grows, that is, the energy decreases, along the gold nanorod array. A Bose-Einstein condensate forms when an energy minimum of the lattice is reached. Credit: Aalto University / Tommi Hakala and Antti Paraoanu

Nearly a hundred years ago, Albert Einstein and Satyendra Nath Bose predicted that quantum mechanics can force a large number of particles to behave in concert as if they were only a single particle. The phenomenon is called Bose-Einstein condensation, and it took until 1995 to create the first such condensate of a gas of alkali atoms. Although Bose-Einstein condensation has been observed in several systems, the limits of the phenomenon need to be pushed further: to faster timescales, higher temperatures, and smaller sizes...

This is Cristiano Nisoli. Credit: Los Alamos National Laboratory

‘Spindoctors’ note that topological order, associated with quantum mechanics, also applies to classical material called artificial spin ice. Physicists have identified a new state of matter whose structural order operates by rules more aligned with quantum mechanics than standard thermodynamic theory. In a classical material called artificial spin ice, which in certain phases appears disordered, the material is actually ordered, but in a “topological” form.

“Our research shows for the first time that classical systems such as artificial spin ice can be designed to demonstrate topological ordered phases, which previously have been found only in quantum conditions,” said Los Alamos National Laboratory physicist Cristiano Nisoli...

Qingdi Wang et al, How the huge energy of quantum vacuum gravitates to drive the slow accelerating expansion of the Universe, Physical Review D (2017). DOI: 10.1103/PhysRevD.95.103504

UBC physicists may have solved one of nature’s great puzzles: what causes the accelerating expansion of our universe? PhD student Qingdi Wang has tackled this question in a new study that tries to resolve a major incompatibility issue between two of the most successful theories that explain how our universe works: quantum mechanics and Einstein’s theory of general relativity. The study suggests that if we zoomed in-way in-on the universe, we would realize it’s made up of constantly fluctuating space and time.

“Space-time is not as static as it appears, it’s constantly moving,” said Wang...