Researchers measure near-perfect performance in low-cost semiconductors

16.03. 2019 Quantum Physics News

Tiny, easy-to-produce particles, called quantum dots, may soon take the place of more expensive single crystal semiconductors in advanced electronics found in solar panels, camera sensors and medical imaging tools. Although quantum dots have begun to break into the consumer market—in the form of quantum dot TVs—they have been hampered by long-standing uncertainties about their quality. Now, a new measurement technique developed by researchers at Stanford University may finally dissolve those doubts.

Speeding up artificial intelligence

15.03. 2019 Quantum Physics News

A group at Politecnico di Milano has developed an electronic circuit able to solve a system of linear equations in a single operation in the timescale of a few tens of nanoseconds. The performance of this new circuit is superior not only to classical digital computers, but also to quantum computers. It will be soon possible to develop a new generation of computing accelerators that will revolutionize the technology of artificial intelligence.

Long-distance quantum information exchange—success at the nanoscale

15.03. 2019 Quantum Physics News

At the Niels Bohr Institute, University of Copenhagen, researchers have realized the swap of electron spins between distant quantum dots. The discovery brings us a step closer to future applications of quantum information, as the tiny dots have to leave enough room on the microchip for delicate control electrodes. The distance between the dots has now become big enough for integration with traditional microelectronics and perhaps, a future quantum computer. The result is achieved via a multinational collaboration with Purdue University and UNSW, Sydney, Australia, now published in Nature Communications.

Quantum sensing method measures minuscule magnetic fields

15.03. 2019 Quantum Physics News

A new way of measuring atomic-scale magnetic fields with great precision, not only up and down but sideways as well, has been developed by researchers at MIT. The new tool could be useful in applications as diverse as mapping the electrical impulses inside a firing neuron, characterizing new magnetic materials, and probing exotic quantum physical phenomena.

Exploring the behavior of a gas as it transitions between quantum and classical states

15.03. 2019 Quantum Physics News

A team of researchers from the MIT-Harvard Center for Ultracold Atoms has developed a way to study and measure gases as they transition between quantum and classical states due to changes in temperature. In their paper published in the journal Physical Review Letters, the group describes experiments they carried out with clouds of lithium-6 atoms and what they found.

Researchers put machine learning on path to quantum advantage

14.03. 2019 Quantum Physics News

There are high hopes that quantum computing's tremendous processing power will someday unleash exponential advances in artificial intelligence. AI systems thrive when the machine learning algorithms used to train them are given massive amounts of data to ingest, classify and analyze. The more precisely that data can be classified according to specific characteristics, or features, the better the AI will perform. Quantum computers are expected to play a crucial role in machine learning, including the crucial aspect of accessing more computationally complex feature spaces – the fine-grain aspects of data that could lead to new insights.

Testing the symmetry of space-time by means of atomic clocks

13.03. 2019 Quantum Physics News

In his Special Theory of Relativity, Einstein formulated the hypothesis according to which the speed of light is always the same, no matter what the conditions are. It may, however, be possible that—according to theoretical models of quantum gravitation—this uniformity of space-time does not apply to particles. Physicists have now tested this hypothesis with a first long-term comparison of two optical ytterbium clocks at the Physikalisch-Technische Bundesanstalt (PTB). With these clocks, whose error amounts to only one second in ten billion years, it should be possible to measure even extremely small deviations of the movement of the electrons in ytterbium. But the scientists did not detect any change when the clocks were oriented differently in space. Due to this result, the current limit for testing the space-time symmetry by means of experiments has been drastically improved by a factor of 100. In addition to this, the extremely small systematic measurement uncertainty of the optical ytterbium clocks of less than 4 × 10-18 has been confirmed. The team consisting of physicists from PTB and from the University of Delaware has published its results in the current issue of Nature.

Quantum-critical conductivity of the Dirac fluid in graphene

13.03. 2019 Quantum Physics News

Graphene is expected to behave like a quantum-critical, relativistic plasma known as "Dirac fluid" near charge neutrality in which massless electrons and holes rapidly collide. In a recent study now published in Science, Patrick Gallagher and co-workers at the departments of physics and materials science in the U.S., Taiwan, China and Japan used on-chip terahertz spectroscopy and measured the frequency-dependent optical conductivity of graphene between 77 K and 300 K electron temperatures for the first time. Additionally, the scientists observed the quantum-critical scattering rate characteristic of the Dirac fluid. At higher doping, Gallagher et al. uncovered two distinct current-carrying modes with zero and nonzero total momenta as a manifestation of relativistic hydrodynamics.

Can artificial intelligence solve the mysteries of quantum physics?

13.03. 2019 Quantum Physics News

Under the direction of Mobileye founder Amnon Shashua, a research group at Hebrew University of Jerusalem's School of Engineering and Computer Science has proven that artificial intelligence (AI) can help us understand the world on an infinitesimally small scale called quantum physics phenomena.

Physicists reverse time using quantum computer

13.03. 2019 Quantum Physics News

Researchers from the Moscow Institute of Physics and Technology teamed up with colleagues from the U.S. and Switzerland and returned the state of a quantum computer a fraction of a second into the past. They also calculated the probability that an electron in empty interstellar space will spontaneously travel back into its recent past. The study is published in Scientific Reports.

Scientists one step closer to a clock that could replace GPS and Galileo

11.03. 2019 Quantum Physics News

Scientists in the Emergent Photonics Lab (EPic Lab) at the University of Sussex have made a breakthrough to a crucial element of an atomic clock—devices which could reduce our reliance on satellite mapping in the future—using cutting-edge laser beam technology. Their development greatly improves the efficiency of the lancet (which in a traditional clock is responsible for counting), by 80% - something which scientists around the world have been racing to achieve.

Quantum physicists succeed in controlling energy losses and shifts

11.03. 2019 Quantum Physics News

Quantum computers need to preserve quantum information for a long time to be able to crack important problems faster than a normal computer. Energy losses take the state of the qubit from one to zero, destroying stored quantum information at the same time. Consequently, scientists all over the globe have traditionally worked to remove all sources of energy loss—or dissipation—from these machines.

Opening the path to scaling silicon quantum computers

11.03. 2019 Quantum Physics News

Research collaboration between UNSW and the University of Sydney has overcome a fundamental hurdle to building quantum computers in silicon, opening the way to further develop the machines at scale.

In-plane coherent control of plasmon resonances for plasmonic switching and encoding

11.03. 2019 Quantum Physics News

Light incident on metallic nanoparticles can initiate the collective motion of electrons, causing a strong amplification of the local electromagnetic field. Such plasmonic resonances have significant roles in biosensing with ability to improve the resolution and sensitivity required to detect particles at the scale of the single molecule. The control of plasmon resonances in metadevices have potential applications in all-optical, light-with-light signal modulation and image processing. Reports have demonstrated the out-of-plane coherent control of plasmon resonances by modulating metadevices in standing waves. In optical devices, light can be transferred along the surfaces for the unprecedented control of plasmons. When oscillations in conducting electrons are coupled with light photons, localized surface plasmon resonances (LSPR) can act as information carriers for nano-sized optical sensors and in computers.

Using quantum measurements to fuel a cooling engine

11.03. 2019 Quantum Physics News

Researchers at the University of Florence and Istituto dei Sistemi Complessi, in Italy, have recently proved that the invasiveness of quantum measurements might not always be detrimental. In a study published in Physical Review Letters, they showed that this invasive quality can actually be exploited, using quantum measurements to fuel a cooling engine.