China is positioning itself to be a world leader in quantum technology, including drafting international standards.
Circa 2016
It is known that faster-than-light (FTL) transmission of energy could be achieved if the transmission were considered in the framework of non-relativistic classical mechanics. Here we show that FTL transmission of energy could also be achieved if the transmission were considered in the framework of non-relativistic quantum mechanics. In our transmission protocol a two-spin Heisenberg model is considered and the energy is transmitted by two successive local unitary operations on the initially entangled spins. Our protocol does not mean that FTL transmission can be achieved in reality when the theory of relativity is considered, but it shows that quantum entanglement can be used in a recyclable way in energy transmission.
Basic science, practical engineering — and an attempt to focus on the most productive lines of effort.
The Sachdev-Ye-Kitaev (SYK) model, an exactly solvable model devised by Subir Sachdev and Jinwu Ye, has recently proved useful for understanding the characteristics of different types of matter. As it describes quantum matter without quasiparticles and is simultaneously a holographic version of a quantum black hole, it has so far been adopted by both condensed matter and high-energy physicists.
Researchers at University of Pisa and the Italian Institute of Technology (IIT) have recently used the SYK model to examine the charging protocols of quantum batteries. Their paper, published in Physical Review Letters, offers evidence of the potential of quantum mechanical resources for boosting the charging process of batteries.
“Previous theoretical studies laid down the idea that entanglement can be used to greatly speed up the charging process of a quantum battery,” Davide Rossini and Gian Marcello Andolina, two of the researchers who carried out the study, told Phys.org, via email. “However, a concrete solid-state model displaying such fast charging was missing, until now.”
In a study published in Physical Review Letters, a team led by academician Guo Guangcan from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) has made progress in high dimensional quantum teleportation. The researchers demonstrated the teleportation of high-dimensional states in a three-dimensional six-photon system.
To transmit unknown quantum states from one location to another, quantum teleportation is one of the key technologies to realize long-distance transmission.
Compared with two-dimensional systems, high-dimensional system quantum networks have the advantages of higher channel capacity and better security. In recent years more and more researchers of the quantum information field have been working on generating efficient generation of high-dimensional quantum teleportation to achieve efficient high-dimensional quantum networks.
O,.o circa 2020.
Their quantum phase battery consists of an n-doped InAs nanowire forming the core of the battery (the pile) and Al superconducting leads as poles. It is charged by applying an external magnetic field, which then can be switched off.
Cristina Sanz-Fernández and Claudio Guarcello, also from CFM, adapted the theory to simulate the experimental findings.
Continue reading “The World’s First Quantum Phase Battery Is Here” »
Looks like living cells may have a lot more surprises to offer. 😃
Seeing our world through the eyes of a migratory bird would be a rather spooky experience. Something about their visual system allows them to ‘see’ our planet’s magnetic field, a clever trick of quantum physics and biochemistry that helps them navigate vast distances.
Now, for the first time ever, scientists from the University of Tokyo have directly observed a key reaction hypothesised to be behind birds’, and many other creatures’, talents for sensing the direction of the planet’s poles.
The Kondo effect influences the electrical resistance of metals at low temperatures and generates complex electronic and magnetic orders. Novel concepts for data storage and processing, such as using quantum dots, are based on this. In 1998, researchers from the United States published spectroscopic studies on the Kondo effect using scanning tunneling microscopy, which are considered ground-breaking and have triggered countless others of a similar kind. Many of these studies may have to be re-examined now that Jülich researchers have shown that the Kondo effect cannot be proven beyond doubt by this method. Instead, another phenomenon is creating precisely the spectroscopic ‘fingerprint’ that was previously attributed to the Kondo effect.
Normally the resistance of metals decreases as the temperature drops. The Kondo effect causes it to rise again below a threshold value typical to the material in question, the so-called Kondo temperature. This phenomenon occurs when magnetic foreign atoms, such as iron, contaminate non-magnetic host metals, such as copper. Simply put, when a current flows, the atomic nuclei are engulfed by electrons. The iron atoms have a quantum mechanical magnetic moment. This causes the electrons in the vicinity to align their spin antiparallel to the moment of the atom at low temperatures and to hang around the cobalt atom like a cloud on a mountaintop. This hinders the flow of the electrons—the electrical resistance then increases. In physics, this is known as entanglement, the strong coupling of the moment of the impurity with the spins of the surrounding electrons.
For mathematicians and computer scientists, 2020 was full of discipline-spanning discoveries and celebrations of creativity. We’d like to take a moment to recognize some of these achievements.
1. A landmark proof simply titled MIP = RE” establishes that quantum computers calculating with entangled qubits can theoretically verify the answers to an enormous set of problems. Along the way, the five computer scientists who authored the proof also answered two other major questions: Tsirelson’s problem in physics, about models of particle entanglement, and a problem in pure mathematics called the Connes embedding conjecture.
Continue reading “2020’s Biggest Breakthroughs in Math and Computer Science” »
A multitasking nanomachine that can act as a heat engine and a refrigerator at the same time has been created by RIKEN engineers. The device is one of the first to test how quantum effects, which govern the behavior of particles on the smallest scale, might one day be exploited to enhance the performance of nanotechnologies.
Conventional heat engines and refrigerators work by connecting two pools of fluid. Compressing one pool causes its fluid to heat up, while rapidly expanding the other pool cools its fluid. If these operations are done in a periodic cycle, the pools will exchange energy and the system can be used as either a heat engine or a fridge.
It would be impossible to set up a macroscale machine that does both tasks simultaneously—nor would engineers want to, says Keiji Ono of the RIKEN Advanced Device Laboratory. “Combining a traditional heat engine with a refrigerator would make it a completely useless machine,” he says. “It wouldn’t know what to do.”
