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The process begins with tiny, nanoscale diamonds that contain a specific type of impurity: a single nitrogen atom where a carbon atom should be, with an empty space right next to it, resulting from a second missing carbon atom. This “nitrogen vacancy” impurity gives each diamond special optical and electromagnetic properties.

By attaching other materials to the diamond grains, such as metal particles or semiconducting materials known as “quantum dots,” the researchers can create a variety of customizable hybrid nanoparticles, including nanoscale semiconductors and magnets with precisely tailored properties.

“If you pair one of these diamonds with silver or gold nanoparticles, the metal can enhance the nanodiamond’s optical properties. If you couple the nanodiamond to a semiconducting quantum dot, the hybrid particle can transfer energy more efficiently,” said Min Ouyang, an associate professor of physics at UMD and senior author on the study.

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UChicago hasthis been able for the first time conduct an experiment shows the behavior of quantum materials in curved space. In their own words, “We are beginning to make our photons interact with each other. This opens up many possibilities, such as making crystalline or exotic quantum liquid states of light. We can then see how they respond to spatial curvature.”

Interplay of light, matter is of potential technological interest

Continue reading “UChicago Physicists First to See Behavior of Quantum Materials in Curved Space” »

Google is to trying to combine the Adiabatic Quantum computing AQC method with the digital approach’s error-correction capabilities.

The Google team uses a row of nine solid-state qubits, fashioned from cross-shaped films of aluminium about 400 micrometres from tip to tip. These are deposited onto a sapphire surface. The researchers cool the aluminium to 0.02 degrees kelvin, turning the metal into a superconductor with no electrical resistance. Information can then be encoded into the qubits in their superconducting state.

The interactions between neighboring qubits are controlled by ‘logic gates’ that steer the qubits digitally into a state that encodes the solution to a problem. As a demonstration, the researchers instructed their array to simulate a row of magnetic atoms with coupled spin states — a problem thoroughly explored in condensed-matter physics. They could then look at the qubits to determine the lowest-energy collective state of the spins that the atoms represented.

Continue reading “Google team predicts quantum computing supremacy over classical computing around 2018 with a 40 qubit universal quantum computer” »

Scientists at UC San Diego, MIT and Harvard University have engineered “topological plexcitons,” energy-carrying particles that could help make possible the design of new kinds of solar cells and miniaturized optical circuitry.

The researchers report their advance in an article published in the current issue of Nature Communications.

Within the Lilliputian world of solid state physics, light and matter interact in strange ways, exchanging energy back and forth between them.

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Scientists can now identify the exact location of a single atom in a silicon crystal, a discovery that is key for greater accuracy in tomorrow’s silicon based quantum computers.

It’s now possible to track and see individual phosphorus atoms in a silicon crystal allowing confirmation of quantum computing capability, but which also has use in nano detection devices.

Continue reading “World-first pinpointing of atoms at work for quantum computers” »

For months, physicists have been quietly freaking out over tantalising evidence of a brand new particle lying outside the standard model of physics. First seen as a ’blip’ in Large Hadron Collider data, the hunt is now on to confirm its existence, which experts say would be “bigger than the [discovery of the] Higgs boson”.

And physicists have just made the case that another new particle could be waiting to be discovered, by showing that the existence of a mysterious new particle, which they’re calling ‘particle X’, could explain a significant conundrum in physics: where the heck all the missing lithium in the Universe went to.

If you haven’t heard about the case of the missing cosmic lithium, don’t worry, we weren’t across it either. But it turns out that scientists have calculated all the lithium that should have formed in the early Universe, and it’s about three times more lithium than we observe today.

Continue reading “Physicists hint at a mysterious new ‘particle X’ messing with our Universe” »

(Phys.org)—One of the most ambitious endeavors in quantum physics right now is to build a large-scale quantum network that could one day span the entire globe. In a new study, physicists have shown that describing quantum networks in a new way—as mathematical graphs—can help increase the distance that quantum information can be transmitted. Compared to classical networks, quantum networks have potential advantages such as better security and being faster under certain circumstances.

“A worldwide quantum network may appear quite similar to the internet—a huge number of devices connected in a way that allows the exchange of information between any of them,” coauthor Michael Epping, a physicist at the University of Waterloo in Canada, told Phys.org. “But the crucial difference is that the laws of quantum theory will be dominant for the description of that information. For example, the state of the fundamental information carrier can be a superposition of the basis states 0 and 1. By now, several advantages in comparison to classical information are known, such as prime number factorization and secret communication. However, the biggest benefit of quantum networks might well be discovered by future research in the rapidly developing field of quantum information theory.”

Quantum networks involve sending entangled particles across long distances, which is challenging because particle loss and decoherence tend to scale exponentially with the distance.

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Optica l quantum technologies are based on the interactions of atoms and photons at the single-particle level, and so require sources of single photons that are highly indistinguishable – that is, as identical as possible. Current single-photon sources using semiconductor quantum dots inserted into photonic structures produce photons that are ultrabright but have limited indistinguishability due to charge noise, which results in a fluctuating electric field. Conversely, parametric down conversion sources yield photons that while being highly indistinguishable have very low brightness. Recently, however, scientists at CNRS — Université Paris-Saclay, Marcoussis, France; Université Paris Diderot, Paris, France; University of Queensland, Brisbane, Australia; and Université Grenoble Alpes, CNRS, Institut Néel, Grenoble, France; have developed devices made of quantum dots in electrically-controlled cavities that provide large numbers of highly indistinguishable photons with strongly reduced charge noise that are 20 times brighter than any source of equal quality. The researchers state that by demonstrating efficient generation of a pure single photon with near-unity indistinguishability, their novel approach promises significant advances in optical quantum technology complexity and scalability.

Dr. Pascale Senellart and Phys.org discussed the paper, Near-optimal single-photon sources in the solid state, that she and her colleagues published in Nature Photonics, which reports the design and fabrication of the first optoelectronic devices made of quantum dots in electrically controlled cavities that provide bright source generating near-unity indistinguishability and pure single photons. “The ideal single photon source is a device that produces light pulses, each of them containing exactly one, and no more than one, photon. Moreover, all the photons should be identical in spatial shape, wavelength, polarization, and a spectrum that is the Fourier transform of its temporal profile,” Senellart tells Phys.org. “As a result, to obtain near optimal single photon sources in an optoelectronic device, we had to solve many scientific and technological challenges, leading to an achievement that is the result of more than seven years of research.”

Continue reading “The path to perfection: Quantum dots in electrically-controlled cavities yield bright, nearly identical photons” »

Riding the coattails of cold atomic physics, researchers have demonstrated the ability to steer cold molecules into desired quantum states.

Ultracold atoms have become a favorite tool in physics because they can be precisely placed in a quantum state using optical and magnetic fields. This quantum control has been crucial for understanding fundamental quantum-mechanical behavior and for creating metrological devices such as the atomic clocks that keep time for GPS systems. Current efforts are devoted to using these controllable systems to simulate, for example, superconductivity, but this and other future applications will likely require that the particles within the system interact with each other. Ultracold atoms do not interact very strongly, so an obvious alternative is to turn to molecules. As opposed to atoms, molecules can have an electric dipole, which lets them naturally interact strongly with each other through dipole forces. But molecules are not a straight substitute for atoms. They are much more complicated and thus significantly harder to cool and control than atoms.