A Quantum Enigma

Scientists have discovered that tantalum, a superconducting metal, significantly improves the performance of qubits in quantum computers. By using x-ray photoelectron spectroscopy, they found that the tantalum oxide layer on qubits was non-uniform, prompting further investigations on how to modify these interfaces to boost overall device performance.





Researchers decode the chemical profile of tantalum surface oxides to enhance understanding of loss mechanisms and to boost the performance of qubits.

Whether it’s baking a cake, constructing a building, or creating a quantum device, the caliber of the finished product is greatly influenced by the components or fundamental materials used. In their pursuit to enhance the performance of superconducting qubits, which form the bedrock of quantum computers, scientists have been probing different foundational materials aiming to extend the coherent lifetimes of these qubits.

Coherence time serves as a metric to determine the duration a qubit can preserve quantum data, making it a key performance indicator. A recent revelation by researchers showed that the use of tantalum in superconducting qubits enhances their functionality. However, the underlying reasons remained unknown – until now.


Scientists from the Center for Functional Nanomaterials (CFN), the National Synchrotron Light Source II (NSLS-II), the Co-design Center for Quantum Advantage (C2QA), and Princeton University investigated the fundamental reasons that these qubits perform better by decoding the chemical profile of tantalum.


The results of this work, which were recently published in the journal Advanced Science, will provide key knowledge for designing even better qubits in the future. CFN and NSLS-II are U.S. Department of Energy (DOE) Office of Science User Facilities at DOE’s Brookhaven National Laboratory. C2QA is a Brookhaven-led national quantum information science research center, of which Princeton University is a key partner.     READ MORE...

Creating Matrer

E = MC2 MAY BE the most quotidian equation in physics. Everyone’s heard of it and it’s been proven time and again. Did you convert mass into energy? Go tell it to the stars, whose light is generated from mass lost during nuclear fusion.

But there is another way to imagine this fundamental equation.

“You can actually look at this process from both sides,” Daniel Brandenburg, a physicist at Brookhaven National Laboratory, tells Inverse.

“In our case, we wanted to take light and convert it into matter.”

That it turns out is a lot less mundane.

On his 143rd birthday, Inverse celebrates the world’s most iconic physicist — and interrogates the myth of his genius. Welcome to Einstein Week.

Brandenburg is a member of the STAR collaboration, a group of more than 700 scientists from 15 countries who use BNL’s Relativistic Heavy Ion Collider, or RHIC (pronounced “Rick”), to smash gold nuclei together at 99.995 percent the speed-of-light.

For this experiment, the researchers were more interested in the near misses than the hits. Ultra-high-energy photons encircle the gold nuclei like an aura, and auras collide as nuclei zoom past one another. When photons (particles of light; massless, pure energy) collide, they generate an electron and a positron, its antimatter counterpart — both particles that have a mass. This is known as the Breit-Wheeler Process.

“The part that makes the Breit-Wheeler process so hard to achieve is getting photons that have enough energy,” explains Brandenburg. “We’ve crossed this threshold where we can convert the photons into a real electron-positron pair. And that’s where we really can achieve what Einstein talked about, where we take the energy from the photons.”

THE EINSTEIN CONNECTION
E = mc2 is an outgrowth of Albert Einstein’s theory of special relativity, which says that an object’s speed affects how it experiences space and time relative to other objects. (His theory of general relativity adds gravity into the mix.) About two decades after Einstein’s seminal 1905 paper on the matter, two theoretical physicists, Gregory Breit and John Wheeler took his by then famous and accepted equation and deduced the requirements for turning light into matter.  READ MORE...

Colliding Photons

Collide light with light, and poof, you get matter and antimatter. It sounds like a simple idea, but it turns out to be surprisingly hard to prove.

A team of physicists is now claiming the first direct observation of the long-sought Breit-Wheeler process, in which two particles of light, or photons, crash into one another and produce an electron and its antimatter counterpart, a positron. 

But like a discussion from an introductory philosophy course, the detection’s significance hinges on the definition of the word “real.” Some physicists argue the photons don’t qualify as real, raising questions about the observation’s implications.

Predicted more than 80 years ago, the Breit-Wheeler process had never been directly observed, although scientists have seen related processes, such as light scattering off of light (SN: 8/14/17). 

New measurements from the STAR experiment at Brookhaven National Laboratory’s Relativistic Heavy Ion Collider match predictions for the elusive transformation, Brookhaven physicist Daniel Brandenburg and colleagues report in the July 30 Physical Review Letters.

“The idea that you can create matter from light smashing together is an interesting concept,” says Brandenburg. 

It’s a striking demonstration of the physics immortalized in Einstein’s equation E=mc2, which revealed that energy and mass are two sides of the same coin.  READ MORE