Scientists have developed the ACE algorithm to study qubit interactions and changes in their quantum state, simplifying quantum dynamics computation and paving the way for advancements in quantum computing and telephony.
Practical quantum computing is another step closer.
Researchers have introduced a novel algorithm called Automated Compression of Arbitrary Environments (ACE) designed to study the interactions of qubits with their surrounding environment and the ensuing changes in their quantum state. By simplifying the computation of quantum dynamics, this algorithm, grounded on Feynman’s interpretation of quantum mechanics, offers new avenues for understanding and harnessing quantum systems. Potential applications include advancements in quantum telephony and computing, providing more precise predictions about quantum coherence and entanglement.
Conventional computers use bits, represented by zeros and ones, to transmit information, whereas quantum computers use quantum bits (qubits) instead. Similar to bits, qubits have two main states or values: 0 and 1. However, unlike a bit, a qubit can exist in both states at the same time.
While this may seem like a baffling paradox, it can be explained through a simple analogy with a coin. A classic bit can be represented as a coin lying with heads or tails (one or zero) facing up, while a qubit can be thought of as a spinning coin, which also has heads and tails, but whether it is heads or tails up can only be determined once it stops spinning, ie loses its original state.
When a spinning coin stops, it can serve as an analogy for a quantum measurement, whereby one of the two states of the qubit is selected. In <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
quantum computing
Performing computation using quantum-mechanical phenomena such as superposition and entanglement.
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>quantum computing, different qubits must be linked together, eg the states 0 (1) of one qubit must be uniquely correlated with the states 0 (1) of another qubit. When the quantum states of two or more objects become correlated, it is called quantum entanglement.
The Challenge of Quantum Entanglement
The main difficulty with quantum computing is that qubits are surrounded by an environment and interact with them. This interaction can cause the quantum entanglement of qubits to degrade, resulting in their disentanglement from one another.
An analogy with two coins can help in understanding this concept. If two identical coins are spun simultaneously and then stopped after a brief period, they may both end up with the same side up, either heads or tails. This synchronicity between spinning coins can be compared to quantum entanglement. However, if the coins continue to spin for a longer duration, they will eventually lose synchronicity and no longer end up with the same side—heads or tails—facing up.
The loss of synchronicity occurs because the spinning coins gradually lose energy, mainly due to friction with the table, and each coin does so in a unique manner. In the quantum world, friction, or the loss of energy due to interaction with the environment, eventually leads to quantum decoherence, meaning a loss of synchronicity between qubits. This results in qubit dephasing, where the phase of the quantum state (represented by the angle of rotation of the coin) changes randomly over time, causing a loss of quantum information and making quantum computing impossible.
Identification of an efficient representation is fully automatic and does not rely on any a priori approximations or assumptions. Credit: Alexei Vagov
Quantum Coherence and Dynamics
A key challenge faced by many researchers today is to preserve quantum coherence for longer periods. This can be achieved by accurately describing the evolution of the quantum state over time, also known as quantum dynamics.
Scientists from the MIEM HSE Centre for Quantum Metamaterials, in collaboration with colleagues from Germany and the UK, have proposed an algorithm called Automated Compression of Arbitrary Environments (ACE) as a solution for studying the interaction of qubits with their environment and the resulting changes in their quantum state over time.
Insight into Quantum Dynamics
“The almost infinite number of vibrational modes or degrees of freedom in the environment makes the computation of quantum dynamics particularly challenging. In fact, this task involves computing the dynamics of a single quantum system while it is surrounded by trillions of others. Direct calculation is impossible in this case, as no computer can handle it.
However, not all changes in the environment carry equal importance: those which occur at a sufficient distance from our quantum system are incapable of affecting its dynamics in major ways. The division into “relevant” and “irrelevant” environmental degrees of freedom lies at the basis of our method,” says Alexei Vagov, co-author of the paper, Director of the MIEM HSE Centre for Quantum Metamaterials.
Feynman’s Interpretation and the ACE Algorithm
According to the interpretation of quantum mechanics proposed by the famous American physicist Richard Feynman, calculating the quantum state of a system involves computing the sum of all possible ways in which the state can be achieved. This interpretation assumes that a quantum particle (system) can move in all possible directions, including forward or backward, right or left, and even back in time. The quantum probabilities of all such trajectories must be added up to compute the final state of the particle.
“The problem is that there are too many possible trajectories even for one particle, let alone the entire environment. Our algorithm makes it possible to consider only the trajectories which significantly contribute to the qubit’s dynamics while discarding those with negligible contributions. In our method, the evolution of a qubit and its environment is captured by tensors, which are matrices or tables of numbers that describe the state of the entire system at different points in time. We then select only those portions of the tensors which are relevant to the system’s dynamics,” explains Alexei Vagov.
Conclusion: Implications of the ACE Algorithm
The researchers emphasize that the Automated Compression of Arbitrary Environments algorithm is publicly available and implemented as computer code. According to the authors, it opens up entirely new possibilities for the precise computation of the dynamics of multiple quantum systems. In particular, this method makes it possible to estimate the time until entangled <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
photon
A photon is a particle of light. It is the basic unit of light and other electromagnetic radiation, and is responsible for the electromagnetic force, one of the four fundamental forces of nature. Photons have no mass, but they do have energy and momentum. They travel at the speed of light in a vacuum, and can have different wavelengths, which correspond to different colors of light. Photons can also have different energies, which correspond to different frequencies of light.
” data-gt-translate-attributes=”["attribute":"data-cmtooltip", "format":"html"]”>photon pairs in quantum telephony lines will become disentangled, the distance to which a quantum particle can be “teleported,” or how long it can take for the qubits of a quantum computer to lose coherence.
Reference: “Simulation of open quantum systems by automated compression of arbitrary environments” by Moritz Cygorek, Michael Cosacchi, Alexei Vagov, Vollrath Martin Axt, Brendon W. Lovett, Jonathan Keeling and Erik M. Gauger, 24 March 2022, <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
Nature Physics
As the name implies, Nature Physics is a peer-reviewed, scientific journal covering physics and is published by Nature Research. It was first published in October 2005 and its monthly coverage includes articles, letters, reviews, research highlights, news and views, commentaries, book reviews, and correspondence.
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
