Lifeboat Foundation

What good is a powerful computer if you can’t read its output? Or readily reprogram it to do different jobs? People who design quantum computers face these challenges, and a new device may make them easier to solve.

The device, introduced by a team of scientists at the National Institute of Standards and Technology (NIST), includes two superconducting quantum bits, or qubits, which are a quantum computer’s analog to the logic bits in a classical computer’s processing chip. The heart of this new strategy relies on a “toggle switch” device that connects the qubits to a circuit called a “readout resonator” that can read the output of the qubits’ calculations.

This toggle switch can be flipped into different states to adjust the strength of the connections between the qubits and the readout resonator. When toggled off, all three elements are isolated from each other. When the switch is toggled on to connect the two qubits, they can interact and perform calculations. Once the calculations are complete, the toggle switch can connect either of the qubits and the readout resonator to retrieve the results.

The images shed light on how electrons form superconducting pairs that glide through materials without friction.

When your laptop or smartphone heats up, it’s due to energy that’s lost in translation. The same goes for power lines that transmit electricity between cities. In fact, around 10 percent of the generated energy is lost in the transmission of electricity. That’s because the electrons that carry electric charge do so as free agents, bumping and grazing against other electrons as they move collectively through power cords and transmission lines. All this jostling generates friction, and, ultimately, heat.

But when electrons pair up, they can rise above the fray and glide through a material without friction. This “superconducting” behavior occurs in a range of materials, though at ultracold temperatures. If these materials can be made to superconduct closer to room temperature, they could pave the way for zero-loss devices, such as heat-free laptops and phones, and ultra-efficient power lines. But first, scientists will have to understand how electrons pair up in the first place.

Nematicity was recently found in the kagome superconductor CsV3Sb5. Here, by performing elastoresistance measurements on Ti-doped CsV3Sb5, the authors find that nematic fluctuations play an important role in enhancing superconductivity in this material.

Pump-probe spectroscopy is a versatile technique to explore ultrafast dynamics on the femtosecond timescale. Here the authors report a pump-probe experiment and quantum modeling combined study revealing dynamics of collective polaritonic states that are formed between a molecular photoswitch and plasmonic nanoantennas.

“A phonon represents the collective motion of an astronomical number of atoms,” Cleland says. “And they all have to work together in order to obey quantum mechanics. There was this question in the back of my mind, will this really work? We tried it, and it’s kind of amazing, but it really does work.”

Splitting a phonon

The team created single phonons as propagating wavepackets on the surface of a lithium niobate chip. The phonons were created and detected using two superconducting qubits, which were located on a separate chip, and coupled to the lithium niobate chip through the air. The two superconducting qubits were located either of the chip, with a two-millimetre-long channel between them hosting the travelling phonons.

A group of 51 superconducting qubits have been entangled inside a quantum computer, not just in pairs but in a complex system that entangles each qubit to every other one.

By Karmela Padavic-Callaghan

The quantum nature of interactions between elementary particles allows drawing non-trivial conclusions even from processes as simple as elastic scattering. The ATLAS experiment at the LHC accelerator reports the measurement of fundamental properties of strong interactions between protons at ultra-high energies.

The physics of billiard ball collisions is taught from early school years. In a good approximation, these collisions are elastic, where both momentum and energy are conserved. The scattering angle depends on how central the collision was (this is often quantified by the impact parameter value—the distance between the centers of the balls in a plane perpendicular to the motion). In the case of a small impact parameter, which corresponds to a highly central collision, the scattering angles are large. As the impact parameter increases, the scattering angle decreases.

In particle physics, we also deal with elastic collisions, when two particles collide, maintaining their identities, and scatter a certain angle to their original direction of motion. Here, we also have a relationship between the collision parameter and the scattering angle. By measuring the scattering angles, we gain information about the spatial structure of the colliding particles and the properties of their interactions.

All biological systems are wildly disordered. Yet somehow, that disorder enables plant photosynthesis to be nearly 100% efficient.

Advancing the state of the art in superconducting qubit hardware requires knowledge across a range of disciplines, including materials, fabrication, circuit design and simulation, packaging, cryogenics, low-noise measurement, hardware-software interfacing, and quantum compilation. As understanding of materials and processes has advanced over time, fabricating the highest-quality qubits increasingly relies on millions of dollars of fabrication equipment and countless hours of process development and sustainment.

“It has become increasingly challenging for individual organizations to maintain this full stack of expertise, particularly as circuits become more complex to design, fabricate, and measure,” Schwartz says. “As a result, superconducting qubit hardware research has remained centralized into a relatively small number of laboratories and large universities capable of developing and sustaining this expertise.”

MIT Lincoln Laboratory is one of these laboratories, with more than 20 years of research and development in superconducting qubits and demonstrations of world-leading qubit performance. The qubits are made on-site at the Microelectronics Laboratory, considered to be one of the U.S. government’s most advanced foundries, and in specialized prototyping facilities. The collective expertise and equipment of this facility have made it possible to stand-up the SQUILL Foundry.