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Category: computing – Page 432

Toward large-scale fault-tolerant universal photonic quantum computing

Year 2019 face_with_colon_three

Photonic quantum computing is one of the leading approaches to universal quantum computation. However, large-scale implementation of photonic quantum computing has been hindered by its intrinsic difficulties, such as probabilistic entangling gates for photonic qubits and lack of scalable ways to build photonic circuits. Here, we discuss how to overcome these limitations by taking advantage of two key ideas which have recently emerged. One is a hybrid qubit-continuous variable approach for realizing a deterministic universal gate set for photonic qubits. The other is the time-domain multiplexing technique to perform arbitrarily large-scale quantum computing without changing the configuration of photonic circuits. These ideas together will enable scalable implementation of universal photonic quantum computers in which hardware-efficient error correcting codes can be incorporated. Furthermore, all-optical implementation of such systems can increase the operational bandwidth beyond terahertz in principle, ultimately enabling large-scale fault-tolerant universal quantum computers with ultrahigh operation frequency.

New Measurements Provide a Glimpse of the Quantum Future

A multi-institutional team has created an efficient method for measuring high-dimensional qudits encoded in quantum frequency combs, a kind of photon source, on a single optical chip using already available experimental and computational resources.

Despite the fact that the word “qudit” may appear to be a typo, this less well-known relative of the qubit, or quantum bit, has the ability to carry more data and is more noise-resistant, two crucial characteristics required to enhance the performance of quantum networks, quantum key distribution systems, and eventually the quantum internet.

In contrast to traditional computer bits, which classify data as ones or zeros, qubits can hold values of one, zero, or both. This is due to superposition, a phenomenon that enables several quantum states to exist simultaneously. Qudit’s “d” refers to the variety of levels or values that may be encoded on a photon. Traditional qubits only have two levels, but by adding more levels, they become qudits.

AMD Radeon RX 7800 and RX 7700 graphics likely to rely on high clocks for performance

An update for AMD’s ROCm general-purpose GPU software has reportedly revealed the specs for Navi 32 and Navi 33, (opens in new tab) the next graphics chips likely to be released in the RDNA 3 series, otherwise known as Radeon RX-7000 series. Exactly where the new chips will slot into AMD’s new Radeon RX 7000-series (opens in new tab) is the really big question.

Are these chips the basis of the upcoming Radeon RX 7,800 and 7,700 GPUs? Hold that thought while we consider the new information that’s emerged. Buried deep within an ROCm file called “performance.hpp” are references to both Navi 32 and Navi. But the really critical numbers listed in the file are 60 and 32, and we’re talking CUs or Compute Units. To make sense of those numbers, the Navi 31 chip inside the AMD Radeon RX 7,900 XT and XTX graphics cards runs 96 CUs.

A Diamond “Blanket” Can Cool the Transistors Needed for 6G

“Thermal issues are currently one of the biggest bottlenecks that are plaguing any kind of microelectronics,” says team lead Srabanti Chowdhury, professor of electrical engineering at Stanford University. “We asked ourselves, ‘Can we perform device cooling at the very material level without paying a penalty in electrical performance?’”

Indeed, they could. The engineers grew a heat-wicking diamond layer right on top of individual transistors—their hottest points—as well as on their sides. Heat flowed through the diamond to a heat sink on the back of the device. With this technique, the researchers achieved temperatures 100 degrees Celsius lower without any degradation of the device’s electrical properties. They will report their findings in San Francisco at the IEEE International Electron Device Meeting in December.

They demonstrated their technique on gallium nitride (GaN) high-electron-mobility transistors, or HEMTs. GaN is the go-to alternative to silicon for high-frequency applications, as it can sustain higher electric fields and responds more quickly to electric field changes. GaN also breaks down at a higher temperature than silicon. But not high enough: “If you go by the physics of the material, you see what its potential is, and we’re nowhere close to that today,” says Chowdhury. Keeping GaN HEMTs cool as devices shrink and frequencies grow will allow them to live up to their physics-promised potential.

Apple Watch Ultra becomes a diving computer with launch of Oceanic+

In September, Apple announced a new wearable called the Apple Watch Ultra, and one of the company’s key pitches for the device was its use as a diving computer. Now Oceanic+, the app that makes that feature possible, launched exclusively for the Ultra, Apple announced today.

A lot of the features focus on either planning dives in advance or viewing dive reports after you’re done, but for those that you use underwater, the app utilizes haptics to send you alerts. The Watch Ultra’s very bright screen can help with legibility underwater, too.

A scalable quantum memory with a lifetime over 2 seconds and integrated error detection

Quantum memory devices can store data as quantum states instead of binary states, as classical computer memories do. While some existing quantum memory technologies have achieved highly promising results, several challenges will need to be overcome before they can be implemented on a large scale.

Researchers at the AWS Center for Quantum Networking and Harvard University have recently developed a promising capable of error detection and with a lifetime or coherence time (i.e., the time for which a quantum memory can hold a superposition without collapsing) exceeding 2 seconds. This memory, presented in a paper in Science, could pave the way towards the creation of scalable quantum networks.

Quantum networks are systems that can distribute entangled , or qubits, to users who are in different geographic locations. While passing through the networks, qubits are typically encoded as photons (i.e., single particles of light).

New magnetometer designed to be integrated into microelectronic chips

Researchers at the UPC’s Department of Electronic Engineering have developed a new type of magnetometer that can be integrated into microelectronic chips and that is fully compatible with the current integrated circuits. Of great interest for the miniaturization of electronic systems and sensors, the study has been recently published in Microsystems & Nanoengineering.

Microelectromechanical systems (MEMS) are electromechanical systems miniaturized to the maximum, so much so that they can be integrated into a chip. They are found in most of our day-to-day devices, such as computers, car braking systems and mobile phones. Integrating them into has clear advantages in terms of size, cost, speed and energy efficiency. But developing them is expensive, and their performance is often compromised by incompatibilities with other electronic systems within a device.

MEMS can be used, among many others, to develop magnetometers—a device that measures to provide direction during navigation, much like a compass—for integration into smartphones and wearables or for use in the automotive industry. Therefore, one of the most promising lines of work are Lorentz force MEMS magnetometers.

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