Researchers at the Kastler Brossel Laboratory in Paris have succeeded in implementing a novel “hybrid” entanglement swapping protocol, bringing within reach the connection of disparate platforms in a future, heterogeneously structured, quantum internet.
Quantum engineers from UNSW Sydney have created artificial atoms in silicon chips that offer improved stability for quantum computing, according to a news release.
In a paper published today in Nature Communications, UNSW quantum computing researchers describe how they created artificial atoms in a silicon ‘quantum dot’, a tiny space in a quantum circuit where electrons are used as qubits (or quantum bits), the basic units of quantum information.
Scientia Professor Andrew Dzurak explains that unlike a real atom, an artificial atom has no nucleus, but it still has shells of electrons whizzing around the centre of the device, rather than around the atom’s nucleus.
An international team of scientists uncovered exotic quantum properties hidden in magnetite, the oldest magnetic material known to mankind. The study reveals the existence of low-energy waves that indicate the important role of electronic interactions with the crystal lattice. This is another step to fully understand the metal-insulator phase transition mechanism in magnetite, and in particular to learn about the dynamical properties and critical behavior of this material in the vicinity of the transition temperature.
Magnetite (FeO4) is a common mineral, whose strong magnetic properties were already known in ancient Greece. Initially, it was used mainly in compasses, and later in many other devices, such as data recording tools. It is also widely applied to catalytic processes. Even animals benefit from the properties of magnetite in detecting magnetic fields – for example, birds are known to use it in navigation.
Physicists are also very interested in magnetite because around a temperature of 125 K it shows an exotic phase transition, named after the Dutch chemist Verwey. This Verwey transition was also the first phase metal-to-insulator transformation observed historically. During this extremely complex process, the electrical conductivity changes by as much as two orders of magnitude and a rearrangement of the crystal structure takes place. Verwey proposed a transformation mechanism based on the location of electrons on iron ions, which leads to the appearance of a periodic spatial distribution of Fe2+ and Fe3+ charges at low temperatures.
Einstein’s equations describe three canonical configurations of space-time. Now one of these three — important in the study of quantum gravity — has been shown to be inherently unstable.
Chinese tech giant’s Paddle Quantum development toolkit now is available on GitHub, enabling developers to build and train quantum neural network models, and includes quantum computing applications.
Study co-led by Berkeley Lab reveals how wavelike plasmons could power up a new class of sensing and photochemical technologies at the nanoscale.
Wavelike, collective oscillations of electrons known as “plasmons” are very important for determining the optical and electronic properties of metals.
In atomically thin 2D materials, plasmons have an energy that is more useful for applications, including sensors and communication devices, than plasmons found in bulk metals. But determining how long plasmons live and whether their energy and other properties can be controlled at the nanoscale (billionths of a meter) has eluded many.
Waves, whether they are light waves, sound waves, or any other kind, travel in the same manner in forward and reverse directions—this is known as the principle of reciprocity. If we could route waves in one direction only—breaking reciprocity—we could transform a number of applications important in our daily lives. Breaking reciprocity would allow us to build novel “one-way” components such as circulators and isolators that enable two-way communication, which could double the data capacity of today’s wireless networks. These components are essential to quantum computers, where one wants to read a qubit without disturbing it. They are also critical to radar systems, whether in self-driving cars or those used by the military.
A team led by Harish Krishnaswamy, professor of electrical engineering, is the first to build a high-performance non-reciprocal device on a compact chip with a performance 25 times better than previous work. Power handling is one of the most important metrics for these circulators and Krishnaswamy’s new chip can handle several watts of power, enough for cellphone transmitters that put out a watt or so of power. The new chip was the leading performer in a DARPA SPAR (Signal Processing at RF) program to miniaturize these devices and improve performance metrics. Krishnaswamy’s group was the only one to integrate these non-reciprocal devices on a compact chip and also demonstrate performance metrics that were orders of magnitude superior to prior work. The study was presented in a paper at the IEEE International Solid-State Circuits Conference in February 2020, and published May 4, 2020, in Nature Electronics.
“For these circulators to be used in practical applications, they need to be able to handle watts of power without breaking a sweat,” says Krishnaswamy, whose research focuses on developing integrated electronic technologies for new high-frequency wireless applications. “Our earlier work performed at a rate 25 times lower than this new one—our 2017 device was an exciting scientific curiosity but it was not ready for prime time. Now we’ve figured out how to build these one-way devices in a compact chip, thus enabling them to become small, low cost, and widespread. This will transform all kinds of electronic applications, from VR headsets to 5G cellular networks to quantum computers.”
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NASA has conducted an experiment in Antarctica, which has revealed new evidence that a parallel universe exists, except the rules of physics, are the opposite of ours.
Physicists have been debating among one another since 1952 of the possibility of a multiverse, whereby many universes exist parallel to ours. These universes could have different laws of physics, or even be similar to ours — just with different timelines.
The original theory was proposed by Quantum science pioneer Erwin Schrodinger, and even he admitted that he might have seemed a little crazy when he hosted that lecture. But now a new discovery has pushed scientists to reconsider if his theory is really as far-fetched as they thought it was. A cosmic ray detection experiment in Antarctica found a particle that very well may be from another universe.
Decoherence is the bane of quantum technologies. In coherent systems, the phase of the wave functions representing the quantum states of particles in the system have definite relations between each other. This allows quantum devices to operate in a meaningful way that differs from classical devices. However, interacting with the world around us rapidly leads to decoherence, which makes it harder to exploit quantum effects for enhancing computation efficiency or communication security. Research has shown that quantum systems with impressively long coherence times are possible in diamond, but diamond is far from the favorite for manufacturers. Now, researchers at the University of Science and Technology in Hefei and Wuhan University in China have demonstrated SiC can boast some of the quantum merits of diamond with the additional advantage of optical control at the wavelengths used by the telecommunications industry.
The defects prized for quantum technologies are nitrogen-vacancy (NV) centers, in which a carbon atom in diamond is replaced by a nitrogen with a missing carbon at the neighboring crystal lattice site. What makes this kind of defect interesting for quantum technologies is that you can control its quantum spin states with light and produce photon-spin entanglement with long coherence times, even at room temperature. The difficulties arise when trying to position the technology in the real world as opposed to the lab. The photon-spin interactions for NV centers in diamond need light at visible wavelengths—telecommunications wavelengths are much longer. In addition, these finely engineered devices need to be hacked out of one of the hardest (and most expensive) materials known to man, one that industry does not have established nanofabrication protocols for.
It turns out there are types of defects in SiC that might also be useful for quantum technologies. SiC is widely used in power electronics, so commercially viable avenues for producing SiC devices already exist. Over the past 10 years, vacancies and divacancies (where one or a pair of atoms in the lattice are absent) in SiC began to attract interest when researchers learned that they could also control their spin states with light at room temperature with long coherence times. The observation of NV centers in SiC really piqued interest, as these were optically active at the wavelengths used by the telecommunications industry as opposed to the shorter visible wavelengths needed to control the spin states of vacancies and divacancies in SiC.
