Lifeboat Foundation

Researchers at ETH have measured the timing of single writing events in a novel magnetic memory device with a resolution of less than 100 picoseconds. Their results are relevant for the next generation of main memories based on magnetism.

At the Department for Materials of the ETH in Zurich, Pietro Gambardella and his collaborators investigate tomorrow’s memory devices. They should be fast, retain data reliably for a long time and also be cheap. So-called magnetic “random access memories” (MRAM) achieve this quadrature of the circle by combining fast switching via electric currents with durable data storage in magnetic materials. A few years ago researchers could already show that a certain physical effect – the spin-orbit torque – makes particularly fast data storage possible. Now Gambardella’s group, together with the R&D-center IMEC in Belgium, managed to temporally resolve the exact dynamics of a single such storage event – and to use a few tricks to make it even faster.

Magnetizing with single spins.

In a new study, a group of researchers led by Prof. Lior Klein, from the physics department and the Institute of Nanotechnology and Advanced Materials at Bar-Ilan University, has shown that relatively simple structures can support an exponential number of magnetic states—much greater than previously thought. They have additionally demonstrated switching between the states by generating spin currents. Their results may pave the way to multi-level magnetic memory with an extremely large number of states per cell; it could also have application in the development of neuromorphic computing, and more. Their research appears as a featured article on the cover of a June issue of Applied Physics Letters.

Spintronics is a thriving branch of nano-electronics which uses the spin of the electron and its associated magnetic moment in addition to the electron charge used in traditional electronics. The main practical contributions of spintronics are in magnetic sensing and non-volatile magnetic data storage, and researchers are pursuing breakthroughs in developing magnetic-based processing and novel types of magnetic memory.

Spintronics devices commonly consist of magnetic elements manipulated by spin-polarized currents between stable magnetic states. When spintronic devices are used for storing data, the number of stable states sets an upper limit on memory capacity. While current commercial magnetic memory cells have two stable magnetic states corresponding to two memory states, there are clear advantages to increasing this number, as it will potentially allow increasing memory density and enable the design of novel types of memory.

Researchers at MIT have developed a process to manufacture and integrate “artificial atoms” with photonic circuitry, and in doing so, are able to produce the largest quantum chip of its kind.

The atoms, which are created by atomic-scale defects in microscopically thin slices of diamond, allow for the scaling up of quantum chip production.

RELATED: 7 REASONS WHY WE SHOULD BE EXCITED BY QUANTUM COMPUTERS

The brain-computer linkup firm, Neuralink, is set to reveal more about its progress toward its goals.

MIT engineers develop a hybrid process that connects photonics with “artificial atoms,” to produce the largest quantum chip of its type.

Optical frequency synthesizers – systems that output laser beams at precise and stable frequencies – have proven extremely valuable in a variety of scientific endeavors, including space exploration, gas sensing, control of quantum systems, and high-precision light detection and ranging (LIDAR). While they provide unprecedented performance, the use of optical frequency synthesizers has largely been limited to laboratory settings due to the cost, size, and power requirements of their components. To reduce these obstacles to widespread use, DARPA launched the Direct On-Chip Digital Optical Synthesizer (DODOS) program in 2014. Key to the program is the miniaturization of necessary components and their integration into a compact module, enabling broader deployment of the technology while unlocking new applications.

To accomplish its goals, DODOS is leveraging advances in microresonators – tiny structures that store light in microchips – to produce optical frequency combs in compact integrated packages. Frequency combs earn their name by converting a single-color input laser beam into a sequence of many additional colors that are evenly spaced and resemble a hair comb. With a sufficiently wide array of comb “teeth,” innovative techniques to eliminate noise become possible that make combs an attractive option for systems needing precise frequency references.

Until recently, creating frequency combs from microresonators was a complex affair that required sophisticated control schemes, dedicated circuitry, and oftentimes, an expert scientist to carefully observe and fine-tune the operation. This is primarily due to the sensitive properties of the microresonator, which needs the perfect amount of light at a special operating frequency – or color – to be provided by an input laser in order for the comb to turn on and even then, producing a coherent or stable comb state could not be guaranteed every time.

A central challenge in developing quantum computers and long-range quantum networks is the distribution of entanglement across many individually controllable qubits¹. Colour centres in diamond have emerged as leading solid-state ‘artificial atom’ qubits^2,3 because they enable on-demand remote entanglement⁴, coherent control of over ten ancillae qubits with minute-long coherence times⁵ and memory-enhanced quantum communication⁶. A critical next step is to integrate large numbers of artificial atoms with photonic architectures to enable large-scale quantum information processing systems. So far, these efforts have been stymied by qubit inhomogeneities, low device yield and complex device requirements. Here we introduce a process for the high-yield heterogeneous integration of ‘quantum microchiplets’—diamond waveguide arrays containing highly coherent colour centres—on a photonic integrated circuit (PIC). We use this process to realize a 128-channel, defect-free array of germanium-vacancy and silicon-vacancy colour centres in an aluminium nitride PIC. Photoluminescence spectroscopy reveals long-term, stable and narrow average optical linewidths of 54 megahertz (146 megahertz) for germanium-vacancy (silicon-vacancy) emitters, close to the lifetime-limited linewidth of 32 megahertz (93 megahertz). We show that inhomogeneities of individual colour centre optical transitions can be compensated in situ by integrated tuning over 50 gigahertz without linewidth degradation. The ability to assemble large numbers of nearly indistinguishable and tunable artificial atoms into phase-stable PICs marks a key step towards multiplexed quantum repeaters^7,8 and general-purpose quantum processors^9,10,11,12.

In the next big step toward complete silicon independence, Apple is planning to dump AMD as a supplier of discrete GPUs in the near future, closely following its decision to dump Intel and the x86 machine architecture in favor of its own SoCs based on the Arm machine architecture. The company is developing its own line of discrete GPUs under the “Metal GPU Family,” a name borrowed from its own Metal graphics API.

This explosive bit of information comes from a WWDC 2020 presentation slide posted by Longhorn (@never_released) on Twitter. The slide suggests that along with the processor, Apple is making a clean break with its graphics hardware. The SoCs powering client-segment Macs, such as future iMacs or MacBooks, could feature iGPUs based on this graphics architecture, while larger platforms such as MacBook Pros, Mac Pros, and iMac Pros of the future could feature Apple’s own discrete GPUs.

Physicists at MIT have designed a quantum “light squeezer” that reduces quantum noise in an incoming laser beam by 15 percent. It is the first system of its kind to work at room temperature, making it amenable to a compact, portable setup that may be added to high-precision experiments to improve laser measurements where quantum noise is a limiting factor.

The heart of the new squeezer is a marble-sized optical cavity, housed in a vacuum chamber and containing two mirrors, one of which is smaller than the diameter of a human hair. The larger mirror stands stationary while the other is movable, suspended by a spring-like cantilever.

The shape and makeup of this second “nanomechanical” mirror is the key to the system’s ability to work at room temperature. When a laser beam enters the cavity, it bounces between the two mirrors. The force imparted by the light makes the nanomechanical mirror swing back and forth in a way that allows the researchers to engineer the light exiting the cavity to have special quantum properties.