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A new kind of 3D optical lattice traps atoms using focused laser spots replicated in multiple planes and could eventually serve as a quantum computing platform.

Researchers have produced 3D lattices of trapped atoms for possible quantum computing tasks, but the standard technology doesn’t allow much control over atom spacing. Now a team has created a new type of 3D lattice by combining optical tweezers—points of focused light that trap atoms—with an optical phenomenon known as the Talbot effect [1]. The team’s 3D tweezer lattice has sites for 10,000 atoms, but with some straightforward modifications, the system could reach 100,000 atoms. Such a large atom arrangement could eventually serve as a platform for a quantum computer with error correction.

3D optical lattices have been around for decades. The standard method for creating them involves crossing six laser beams to generate a 3D interference pattern that traps atoms in either the high-or low-intensity spots (see Synopsis: Pinpointing Qubits in a 3D Lattice). These cold-atom systems have been used as precision clocks and as models of condensed-matter systems. However, the spacing between atoms is fixed by the wavelength of the light, which can limit the control researchers have over the atomic behavior.

An international team of scientists has imaged and analyzed THz waves that propagate in the form of plasmon polaritons along thin anisotropic semiconductor platelets with wavelengths reduced by up to 65 times compared to THz waves in free space.

What’s even more intriguing is that the wavelengths vary with the direction of propagation. Such THz waves can be applied for probing fundamental material properties at the nanometer scale and pave the way to the development of ultra-compact on-chip THz devices. The work has been published in Nature Materials.

Polaritons are hybrid states of light and matter that arise from the coupling of light with matter excitations. Plasmon and phonon polaritons are among the most prominent examples, formed by the coupling of light to collective electron oscillations and crystal lattice vibrations, respectively.

Author and Wordsmith Kel Richards says Quantum computing will do “astonishing things” but the current problem is trying to make them operate at a higher temperature than “below zero centigrade”.

“Quantum computing is apparently … amazingly fast and will do all kinds of astonishing things … the problem at the moment is they have to operate below zero centigrade, otherwise they don’t work, so they’re trying to work out how you can make these really tiny, really fast computers operate at room temperature,” Mr Richards said.

“There is work to be done and if Australia could be in the front of this … brilliant for us.”

Some of Uranus’ moons likely have deep oceans lurking beneath their ice-capped surfaces, a new study by NASA shows.

Two of them, Titania and Oberon, may even have water warm enough to support life.

Scientists have recently pored through decades-old information collected by the veteran Voyager 2 spacecraft, which flew by Uranus in 1986 during its extended space mission. Armed with new computer modeling techniques, researchers reanalyzed the data and concluded four of the ice giant’s 27 moons (opens in a new tab) probably have liquid water sandwiched between their cores and crusts.

AMD CEO, Dr. Lisa Su, states that Moore’s Law is not dead and that innovations such as chiplets & 3D packaging will help overcome the challenges.

Moore’s Law Is Not Dead, Says AMD’s CEO: Working On 3nm, 2nm & Beyond With Latest Innovations

In an interview with Barron’s, AMD CEO, Dr. Lisa Su, points out that Moore’s Law is not dead but has slowed down and things need to be done differently to overcome the performance, efficiency, and cost challenges. AMD has been the pioneer of advancing 3D packaging and chiplet technology with its first HBM designs back in 2015, chiplet processors in 2017, and also the first 3D packaging on a chip with its 3D V-Cache design in 2022.

Perpetual motion machines are impossible, at least in our everyday world. But down at the level of quantum mechanics, the laws of thermodynamics don’t always apply in quite the same way. In 2021, after years of effort, physicists successfully demonstrated the reality of a “time crystal,” a new state of matter that is both stable and ever-changing without any input of energy. In this episode, Steven Strogatz discusses time crystals and their significance with the theoretical physicist Vedika Khemani of Stanford University, who co-discovered that they were possible and then helped to create one on a quantum computing platform.

Listen on Apple Podcasts, Spotify, Google Podcasts, Stitcher, TuneIn or your favorite podcasting app, or you can stream it from Quanta.

Researchers in Germany and the U.S. have shown for the first time that terahertz (THz) light pulses can stabilize ferromagnetism in a crystal at temperatures more than three times its usual transition temperature. As the team reports in Nature, using pulses just hundreds of femtoseconds long (a millionth of a billionth of a second), a ferromagnetic state was induced at high temperature in the rare-earth titanate YTiO₃ which persisted for many nanoseconds after the light exposure. Below the equilibrium transition temperature, the laser pulses still strengthened the existing magnetic state, increasing the magnetization up to its theoretical limit.

Using light to control magnetism in solids is a promising platform for future technologies. Today’s computers mainly rely on the flow of electrical charge to process information. Moreover, digital memory storage devices make use of magnetic bits that must be switched external magnetic fields. Both of these aspects limit the speed and energy efficiency of current computing systems. Using light instead to optically switch memory and computing devices could revolutionize processing speeds and efficiency.

YTiO₃ is a transition metal oxide that only becomes ferromagnetic, with properties resembling those of a fridge magnet, below 27 K or −246°C. At these low temperatures, the spins of the electrons on the Ti atoms align in a particular direction. It is this collective ordering of the spins which gives the material as a whole a macroscopic magnetization and turns it ferromagnetic. In contrast, at temperatures above 27 K, the individual spins fluctuate randomly so that no ferromagnetism develops.

We’re hearing this week from two very different parts of the string theory community that quantum supremacy (quantum computers doing better than classical computers) is the answer to the challenges the subject has faced.

New Scientist has an article Quantum computers could simulate a black hole in the next decade which tells us that “Understanding the interactions between quantum physics and gravity within a black hole is one of the thorniest problems in physics, but quantum computers could soon offer an answer.” The article is about this preprint from Juan Maldacena which discusses numerical simulations in a version of the BFSS matrix model, a 1996 proposal for a definition of M-theory that never worked out. Maldacena points to this recent Monte-Carlo calculation, which claims to get results consistent with expectations from duality with supergravity.

Continue reading “Quantum Supremacy” »

We don’t know when. We don’t know who will get there first. But Q-day will happen — and it will change the world as we know it.