You can’t really enter into “another dimension” as science fiction would have you believe. Instead, dimensions are how we experience the world. But some aspects actually suggest to one expert, not one but two dimensions of time. If it were true, the theory could actually heal the most glaring rift in physics —between quantum mechanics and general relativity.
Posted in computing, quantum physics
Quantum science holds promise for many technological applications, such as building hackerproof communication networks or quantum computers that could accelerate new drug discovery. These applications require a quantum version of a computer bit, known as a qubit, that stores quantum information.
But researchers are still grappling with how to easily read the information held in these qubits and struggle with the short memory time, or coherence, of qubits, which is usually limited to microseconds or milliseconds.
A team of researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory and the University of Chicago has achieved two major breakthroughs to overcome these common challenges for quantum systems. They were able to read out their qubit on demand and then keep the quantum state intact for over five seconds—a new record for this class of devices. Additionally, the researchers’ qubits are made from an easy-to-use material called silicon carbide, which is widely found in lightbulbs, electric vehicles and high-voltage electronics.
If scientists could measure the oscillations of just one energized cesium atom, they’d be able to keep perfect time, but they can’t due to a weird phenomenon called the standard quantum limit.
Instead, they have to measure thousands of atoms at once and then average out the results for atomic clocks, which leads to a just slightly imprecise second.
Now, MIT researchers have found a way to create a more precise atomic clock by exploiting another weird quantum phenomenon: entanglement.
For 15 years, scientists have been baffled by the mysterious way water flows through the tiny passages of carbon nanotubes—pipes with walls that can be just one atom thick. The streams have confounded all theories of fluid dynamics; paradoxically, fluid passes more easily through narrower nanotubes, and in all nanotubes it moves with almost no friction. What friction there is has also defied explanation.
In an unprecedented mashup of fluid dynamics and quantum mechanics, researchers report in a new theoretical study published February 2 in Nature that they finally have an answer: ‘quantum friction.’
The proposed explanation is the first indication of quantum effects at the boundary of a solid and a liquid, says study lead author Nikita Kavokine, a research fellow at the Flatiron Institute’s Center for Computational Quantum Physics (CCQ) in New York City.
On November 16, during its online Quantum Summit, IBM announced that it had successfully completed initial development of the 127-qubit (quantum bit) Eagle quantum computer. Last year, IBM’s Hummingbird quantum computer handled 65 qubits, and, the year before that, the company’s Falcon quantum computer was handling calculations using 27 qubits. So the company has been steadily increasing the number of qubits that its quantum machines can handle, roughly doubling the number of operational qubits in its quantum machines on an annual basis. However, the Eagle quantum computer is the last member of IBM’s Quantum System One family. Designs have reached the limit of the cryogenic refrigerator used to cool the Josephson Junctions that hold the qubits, so IBM has had to work with Bluefors Cryogenics to develop a new, larger cryogenic platform for bigger machines.
If you don’t understand qubits or how quantum computers work, join the club. Nothing in the binary word of today’s digital computers prepares you to understand quantum computing, although there are some superficial similarities. For example, quantum computers store data in qubits just as digital computers store data in bits. However, a bit can store only a “1” or a “0.” Each qubit stores both a “1” and a “0” at the same time in a state of superposition. Consequently, information density is much higher for qubit storage.
Further, qubits can be entangled, a phenomenon that Albert Einstein once described as “spooky action at a distance.” Quantum entanglement, a property of the quantum world, was once the stuff of science fiction. However, it’s quite real and an important part of quantum computing.
An exceptionally large grant will allow a team of Empa researchers to work on an ambitious project over the next ten years: The Werner Siemens Foundation (WSS) is supporting Empa’s CarboQuant project with 15 million Swiss francs. The project aims to lay the foundations for novel quantum technologies that may even operate at room temperature – in contrast to current technologies, most of which require cooling to near absolute zero.
“With this project we are taking a big step into the unknown,” says Oliver Gröning who coordinates the project. “Thanks to the partnership with the Werner Siemens Foundation, we can now move much further away from the safe shore of existing knowledge than would be possible in our ‘normal’ day-to-day research. We feel a little like Christopher Columbus and are now looking beyond the horizon for something completely new.”
The expedition into the unknown now being undertaken by Empa researchers Pascal Ruffieux, Oliver Gröning and Gabriela Borin-Barin under the lead of Roman Fasel was preceded by twelve years of intensive research activity. The researchers from Empa’s [email protected] laboratory, headed by Fasel, regularly published their work in renowned journals such as Nature, Science and Angewandte Chemie.
That is not to say that the advantage has been proven yet. The quantum algorithm developed by IBM performed comparably to classical methods on the limited quantum processors that exist today – but those systems are still in their very early stages.
And with only a small number of qubits, today’s quantum computers are not capable of carrying out computations that are useful. They also remain crippled by the fragility of qubits, which are highly sensitive to environmental changes and are still prone to errors.
Rather, IBM and CERN are banking on future improvements in quantum hardware to demonstrate tangibly, and not only theoretically, that quantum algorithms have an advantage.
Posted in cosmology, quantum physics
In 2014, physicists found evidence of a deep connection between quantum error correction and the nature of space, time and gravity. Generally, gravity is defined as the fabric of space and time but beyond Einstein’s theory, there must be a quantum origin from which the space-time somehow emerges.
The three physicists at the origin of this discovery, Ahmed Almheiri, Xi Dong and Daniel Harlow, suggested that a holographic “emergence” of space-time works just like a quantum error-correcting code. In their paper “Bulk Locality and Quantum Error Correction in AdS/CFT” published in its first version in November 2014, they showed that space-time emerges from this quantum error correction code in an anti-de Sitter (AdS) universes.
The discovery is opening a new way to capture more properties of space-time.
“It is what I would call a dippy process,” Richard Feynman later wrote. “Having to resort to such hocus-pocus has prevented us from proving that the theory of quantum electrodynamics is mathematically self-consistent.”
Justification came decades later from a seemingly unrelated branch of physics. Researchers studying magnetization discovered that renormalization wasn’t about infinities at all. Instead, it spoke to the universe’s separation into kingdoms of independent sizes, a perspective that guides many corners of physics today.
Renormalization, writes David Tong, a theorist at the University of Cambridge, is “arguably the single most important advance in theoretical physics in the past 50 years.”
Quantum computers could cause unprecedented disruption in both good and bad ways, from cracking the encryption that secures our data to solving some of chemistry’s most intractable puzzles. New research has given us more clarity about when that might happen.
Modern encryption schemes rely on fiendishly difficult math problems that would take even the largest supercomputers centuries to crack. But the unique capabilities of a quantum computer mean that at sufficient size and power these problems become simple, rendering today’s encryption useless.
That’s a big problem for cybersecurity, and it also poses a major challenge for cryptocurrencies, which use cryptographic keys to secure transactions. If someone could crack the underlying encryption scheme used by Bitcoin, for instance, they would be able to falsify these keys and alter transactions to steal coins or carry out other fraudulent activity.
