Of all the reasons for wanting to time-travelsaving someone from a fatal mistake, exploring ancient civilizations, gathering evidence about unsolved crimesrecovering lost information isnt the most exciting. But even if a quest to recover the file that didnt auto-save doesn't sound like a Hollywood movie plot, weve all had moments when weve longed to go back in time for exactly that reason.
Theories of time and time-travel have highlighted an apparent stumbling block: time travel requires changing the past, even simply by adding in the time traveller. The problem, according to chaos theory, is that the smallest of changes can cause radical consequences in the future. In this conception of time travel, it wouldnt be advisable to recover your unsaved document since this act would have huge knock-on effects on everything else.
New research in quantum physics from Los Alamos National Laboratory has shown that the so-called butterfly effect can be overcome in the quantum realm in order to unscramble lost information by essentially reversing time.
In a paper published in July, researchers Bin Yan and Nikolai Sinitsyn write that a thought experiment in unscrambling information with time-reversing operations would be expected to lead to the same butterfly effect as the one in the famous Ray Bradburys story A Sound of Thunder In that short story, a time traveler steps on an insect in the deep past and returns to find the modern world completely altered, giving rise to the idea we refer to as the butterfly effect.
In contrast," they wrote, "our result shows that by the end of a similar protocol the local information is essentially restored.
"The primary focus of this work is not 'time travel'physicists do not have an answer yet to tell whether it is possible and how to do time travel in the real world, Yan clarified.
[But] since our protocol involves a 'forward' and a 'backward' evolution of the qubits, achieved by changing the orders of quantum gates in the circuit, it has a nice interpretation in terms of Ray Bradbury's story for the butterfly effect. So, it is an accurate and useful way to understand our results."
What is the butterfly effect?
The world does not behave in a neat, ordered way. If it did, identical events would always produce the same patterns of knock-on effects, and the future would be entirely predictable, or deterministic. Chaos theory claims that the opposite: total randomness is not our situation either. We exist somewhere in the middle, in a world that often appears random but in fact obeys rules and patterns.
Patterns within chaos are hidden because they are highly sensitive to tiny changes, which means similar but not identical situations can produce wildly different outcomes. Another way of putting it is that in a chaotic world, effects can be totally out of proportion to their causes, like the metaphor of a flap of butterfly wings causing a tornado on the other side of the world. On the tornado side of the world, the storm would seem random, because the connection between the butterfly-flap and the tornado is too complex to be apparent. While this butterfly effect is the classic poetic metaphor illustrating chaos theory, chaotic dynamics also play out in real-world contexts, including population growth in the Canadian lynx species and the rotation of Plutos moons.
Another feature of chaos is that, even though the rules are deterministic, the future is not predictable in the long-term. Since chaos is so sensitive to small variations, there are near-infinite ways the rules could play out and we would need to know an impossible amount of detail about the present and past to map out exactly how the world will evolve.
Similarly, you cant reverse-engineer some piece of information about the past simply by knowing the current and even future situations; time-travel doesnt help retrieve past information, because even moving backwards in time, the chaotic system is still in play and will produce unpredictable effects.
Information scrambling
Unscrambling information which has previously been scrambled is not straightforward in a chaotic system. Yan and Sinitsyns key discovery is that it is nonetheless possible in quantum computing to get enough information via time-reversal which will then enable information unscrambling.
According to Yan, the fact that the butterfly effect does not occur in quantum realms is not a surprising result, but demonstrating information unscrambling is both novel and important.
In quantum information theory, scrambling occurs when the information encoded in each quantum particle is split up and redistributed across multiple quantum particles in the same quantum system. The scrambling is not random, since information redistribution relies on quantum entanglement, which means that the states of some quantum particles are dependent on each other. Although the scrambled result is seemingly chaotic, the information can be put back together, at least in principle, using the entangled relationships.
Importantly, information scrambling is not the same as information loss. To continue the earlier analogy: information loss occurs when a document is permanently deleted from your computer. For information scrambling, imagine cutting and pasting tiny bits of one computer file into every other file on your machine. Each file now contains a mess of information snippets. You could reconstruct the original files, if you remembered exactly which bits were cut and pasted, and did the entire process in reverse.
Physicists are interested in information scrambling for two main reasons. On the theoretical side, its been proposed as a way to explain what happens to information sucked into a black hole. On the more applied side, it could be an important mechanism for quantum computers to store and hide information, and could produce fast and efficient quantum simulators, which are used already to perform complex experiments including new drug discovery.
Yan and Sinitsyn fall into the second camp, and construct what they call a practically accessible scenario to test unscrambling by time-travel. This scenario is still hypothetical, but explores the mathematics of the actual quantum processor used by Google to demonstrate quantum supremacy in 2019.
Yan says: Another potential application is to use this effect to protect information. A random evolution on a quantum circuit can make the qubit robust to perturbations. One may further exploit the discovered effect to design protocols in quantum cryptography.
The set-up
In Yan and Sinitsyn's quantum thought experiment, Alice and Bob are the protagonists. Alice is using a simplified version of Googles quantum processor to hide just one part of the information stored on the computer (called the central qubit) by scrambling this qubits state across all the other qubits (called the qubit bath). Bob is cast as the intruder, much like a malicious computer hacker. He wants the important information originally stored on the central qubit, now distributed across entangled quantum particles in the bath.
Unfortunately, Bobs hack, while successful in getting the information he wanted, leaves a trail of destruction.
If her processor has already scrambled the information, Alice is sure that Bob cannot get anything useful, the authors write. However, Bobs measurement changes the state of the central qubit and also destroys all quantum correlations between this qubit and the rest of the system.
Bob's method of information theft has altered the computer state so that Alice can also no longer access the hidden information. In this case, the damage occurs because quantum states contain all possible values they could have, with assigned probabilities of each value, but these possibilities (represented by the wave function) collapse down to just one value when a measurement is taken. Quantum computing relies on unmeasured quantum systems to store even more information in multiple possible states, and Bobs intrusion has totally altered the computer system.
Reversing time
Theoretically, the behaviour of a quantum system moving backwards in time can be demonstrated mathematically using whats called a time-reversed evolution operator, which is exactly what Alice uses to de-scramble the information.
Her time-reversal is not actually time travel the way we understand it from science fiction, it is literally a reversal of times direction; the system evolves backwards following whatever dynamics are in play, rather than Alice herself revisiting an earlier time. If the butterfly effect held in the quantum world, then this backwards evolution would actually increase the damage Bob had caused, and Alice would only be able to retrieve the hidden information if she knew exactly what that damage was and could correct her calculations accordingly.
Luckily for Alice, quantum systems behave totally differently to non-quantum (classical or semiclassical) chaotic systems. What Yan and Sinitsyn found is that she can apply her time-reversal operation and end up at an "earlier" state which will not be identical with the initial system she set up, but it will also not have increased the damage which occurred later. Alice can then reconstruct her initial system using a method of quantum unscrambling called quantum state tomography.
What this means is that a quantum system can effectively heal and even recover information that was scrambled in the past, without the chaos of the butterfly effect.
Classical chaotic evolution magnifies any state damage exponentially quickly, which is known as the butterfly effect, explain Yan and Sinitsyn. The quantum evolution, however, is
linear. This explains why, in our case, the uncontrolled damage to the state is not magnified by the subsequent complex evolution. Moreover, the fact that Bobs measurement does not damage the useful information follows from the property of entanglement correlations in the scrambled state.
Hypothetical though this scenario may be, the result already has a practical use: verifying whether a quantum system has achieved quantum supremacy. Quantum processors can simulate time-reversal in a way that classical computers cannot, which could provide the next important test for the quantum race between Google and IBM.
So, while time travel is still not in the cards, the quantum world continues to mess with our classical conception of how the world evolves in time, and pushes the limits of computing information.
See the original post here:
Scientists Have Shown There's No 'Butterfly Effect' in the Quantum World - VICE
- Netflixs 3 Body Problem: The science explained by an astrophysicist - Vox.com - March 24th, 2024 [March 24th, 2024]
- Entanglement entropies of nuclear systems gro - EurekAlert - March 24th, 2024 [March 24th, 2024]
- The Quest for a Theory of Everything Scientists Put Einstein to the Test - SciTechDaily - March 24th, 2024 [March 24th, 2024]
- Vibrating atoms are seen 'tuning' the energy of a single electron - Earth.com - March 24th, 2024 [March 24th, 2024]
- Innovator Spotlight: Joseph Maciejko | The Quad - University of Alberta - March 24th, 2024 [March 24th, 2024]
- A Breakthrough in the Control of Quantum Phenomena at Room Temperature Has Been Achieved, Researchers Say - The Debrief - February 16th, 2024 [February 16th, 2024]
- The End of the Quantum Ice Age: Room Temperature Breakthrough - SciTechDaily - February 16th, 2024 [February 16th, 2024]
- Quantum computer outperformed by new traditional computing - Earth.com - February 16th, 2024 [February 16th, 2024]
- URI program to help STEM professionals pivot into quantum information science careers - The University of Rhode Island - February 16th, 2024 [February 16th, 2024]
- Quantum realm controlled at room temperature for the first time - Earth.com - February 16th, 2024 [February 16th, 2024]
- Quantum Breakthrough: New Method Preserves Information Against All Odds - SciTechDaily - February 16th, 2024 [February 16th, 2024]
- Quantum computers get new design that makes them more "useful" - Earth.com - February 16th, 2024 [February 16th, 2024]
- Beyond Classical Physics: Scientists Discover New State of Matter With Chiral Properties - SciTechDaily - February 16th, 2024 [February 16th, 2024]
- Quantum research sheds light on the mystery of high-temperature superconductivity - Tech Explorist - February 16th, 2024 [February 16th, 2024]
- Unlocking the Mysteries of Quantum Many-Body Systems: A Look at Quantum Simulators and Universal Scaling ... - Medriva - February 16th, 2024 [February 16th, 2024]
- Functioning quantum internet makes giant stride closer to reality - Earth.com - February 13th, 2024 [February 13th, 2024]
- Exploring New Futures in Space: A Revolutionary Integration of Neuroscience, Quantum Physics, and Space Exploration - SETI Institute - February 13th, 2024 [February 13th, 2024]
- Uncovering the Quantum Plateau: Significance and Implications | Nature Physics - Medriva - February 13th, 2024 [February 13th, 2024]
- The State of the Art in Quantum Computing - Medium - February 13th, 2024 [February 13th, 2024]
- Beyond the Visible Universe: New Research Reveals How Gravity Influences the Quantum Realm - SciTechDaily - February 13th, 2024 [February 13th, 2024]
- Leader of IBM's Quantum Safe Team to speak at URI - University of Rhode Island - September 23rd, 2023 [September 23rd, 2023]
- University Assistant Predoctoral, Physics job with UNIVERSITY OF ... - Times Higher Education - September 23rd, 2023 [September 23rd, 2023]
- Zentropy A New Theory That Could Transform Material Science - SciTechDaily - September 23rd, 2023 [September 23rd, 2023]
- Researchers Studying the Quantum Realm Observe Alice in ... - The Debrief - September 23rd, 2023 [September 23rd, 2023]
- Augusta University graduate starts business in the artificial ... - Jagwire Augusta - September 23rd, 2023 [September 23rd, 2023]
- Quantum Echoes: A Revolutionary Method to Store Information as Sound Waves - SciTechDaily - August 14th, 2023 [August 14th, 2023]
- 'Quantum superchemistry' observed for the 1st time ever - Space.com - August 14th, 2023 [August 14th, 2023]
- Quantum Avalanche A Phenomenon That May Revolutionize Microelectronics and Supercomputing - SciTechDaily - August 14th, 2023 [August 14th, 2023]
- Applications of quantum mechanics at the beach - Symmetry magazine - August 14th, 2023 [August 14th, 2023]
- Book Review: On the Origin of Time Stephen Hawking's Final Theory - Moose Jaw Today - August 14th, 2023 [August 14th, 2023]
- Harnessing Quantum Technologies: The Next Big Leap in Global ... - Fagen wasanni - August 14th, 2023 [August 14th, 2023]
- The quantum avalanche - At the Vienna University of Technology, it ... - Chemie.de - August 14th, 2023 [August 14th, 2023]
- Semiconductors: The Linchpin of AI in Quantum Computing - Fagen wasanni - August 14th, 2023 [August 14th, 2023]
- The Promising Collaboration Between AI and Quantum Computing - Fagen wasanni - August 14th, 2023 [August 14th, 2023]
- String theory physicist changed quantum field theory - USC Dornsife College of Letters, Arts and Sciences - August 14th, 2023 [August 14th, 2023]
- QUANTUM SUPERCOMPUTERS. The words Quantum and ... - Medium - August 14th, 2023 [August 14th, 2023]
- Fourteen MIT School of Science professors receive tenure for 2022 ... - MIT News - August 14th, 2023 [August 14th, 2023]
- The Fascinating World of Quantum Integrated Circuits: The Next Big ... - Fagen wasanni - August 14th, 2023 [August 14th, 2023]
- Conclusive Evidence for Modified Gravity: Collapse of Newton's and ... - SciTechDaily - August 14th, 2023 [August 14th, 2023]
- Physicists Open New Path to an Exotic Form of Superconductivity - SciTechDaily - August 14th, 2023 [August 14th, 2023]
- The Principle of Least Action Now Exists in the Quantum Realm - Popular Mechanics - June 10th, 2023 [June 10th, 2023]
- Quantum materials: Electron spin measured for the first time - EurekAlert - June 10th, 2023 [June 10th, 2023]
- Life in a hologram | MIT News | Massachusetts Institute of Technology - MIT News - June 10th, 2023 [June 10th, 2023]
- If Black Holes Evaporate, Everything Evaporates - Universe Today - June 10th, 2023 [June 10th, 2023]
- Clever Ant-Man Easter Egg Links The Movie to the Real World's ... - Startefacts - June 10th, 2023 [June 10th, 2023]
- Quantum Cryptography: The Cutting Edge of Secure Communication - CityLife - June 10th, 2023 [June 10th, 2023]
- This 17-year-old works to make quantum mainstream - Indiatimes.com - June 10th, 2023 [June 10th, 2023]
- The multiverse is doomed and even Spider-Man and The Flash can't save it - Yahoo Entertainment - June 10th, 2023 [June 10th, 2023]
- Physics of Time Travel: A Scientific Perspective - Mirage News - June 10th, 2023 [June 10th, 2023]
- Quantum Spin Liquids: The Future of Superconductors - EnergyPortal.eu - June 10th, 2023 [June 10th, 2023]
- Interview: Three Books That Make Tess Gunty Angry - The New York Times - June 10th, 2023 [June 10th, 2023]
- Events Calendar School of Mathematics and Statistics Colloquium ... - Carleton University - June 10th, 2023 [June 10th, 2023]
- Graphene and Quantum Computing: A Match Made in Heaven - CityLife - June 10th, 2023 [June 10th, 2023]
- A Quantum Computer Simulation Has Reversed Time And Physics May Never Be The Same - Twisted Sifter - June 2nd, 2023 [June 2nd, 2023]
- Realizing the Einstein-Podolsky-Rosen Paradox for Atomic Clouds - Physics - June 2nd, 2023 [June 2nd, 2023]
- The US and UK team up to advance quantum information science - Fermi National Accelerator Laboratory - June 2nd, 2023 [June 2nd, 2023]
- How plants can perform feats of quantum mechanics - Big Think - June 2nd, 2023 [June 2nd, 2023]
- Physicists Make Matter out of Light to Find Quantum Singularities - Scientific American - June 2nd, 2023 [June 2nd, 2023]
- Eventually everything will evaporate, not only black holes - Science Daily - June 2nd, 2023 [June 2nd, 2023]
- Julius-Maximillians-Universitt Wrzburg Researchers Use ... - HPCwire - June 2nd, 2023 [June 2nd, 2023]
- TNTs The Lazarus Project Uses Suspense Trapping to Ask Smart ... - Roger Ebert - June 2nd, 2023 [June 2nd, 2023]
- Quantum Exponential: building a cutting edge quantum technology ... - The Armchair Trader - June 2nd, 2023 [June 2nd, 2023]
- IMDEA Software and IMDEA Networks work to deploy in the ... - EurekAlert - June 2nd, 2023 [June 2nd, 2023]
- Ian Hacking, Eminent Philosopher of Science and Much Else, Dies ... - The New York Times - June 2nd, 2023 [June 2nd, 2023]
- Does mass increase when nearing the speed of light? - Big Think - June 2nd, 2023 [June 2nd, 2023]
- Answering Questions about Boring Numbers, Disasters, Fusion, and ... - Scientific American - June 2nd, 2023 [June 2nd, 2023]
- Spiderman: Across the Spider-verse | Reel World | timesnewspapers ... - Webster-Kirkwood Times, Inc. - June 2nd, 2023 [June 2nd, 2023]
- There's a Secret Way to Get to Absolute Zero. Scientists Just Found It. - Popular Mechanics - May 6th, 2023 [May 6th, 2023]
- Photon Precision: How Quantum Physicists Shattered the Bounds of Sensitivity - SciTechDaily - May 6th, 2023 [May 6th, 2023]
- Do we live in a hologram? Why physics is still mesmerised by this idea - New Scientist - May 6th, 2023 [May 6th, 2023]
- Is Ultimate Truth an Equation? Nah. The Stute - The Stute - May 6th, 2023 [May 6th, 2023]
- UChicago Lab Creates 'Quantum Casino,' a Win-Win to Educate and ... - Polsky Center for Entrepreneurship and Innovation - May 6th, 2023 [May 6th, 2023]
- Physics - Tweezers in Three Dimensions - Physics - May 6th, 2023 [May 6th, 2023]
- Brave new world: On the edge of a second quantum revolution - University of Cape Town News - May 6th, 2023 [May 6th, 2023]
- Researchers pull back the quantum curtain on 'Weyl fermions' - Phys.org - May 6th, 2023 [May 6th, 2023]
- Scale separation: Breaking down unsolvable problems into solvable ones - Phys.org - May 6th, 2023 [May 6th, 2023]
- Postdoctoral Research Associate in Quantum Optics job with ... - Times Higher Education - May 6th, 2023 [May 6th, 2023]
- Australia's first quantum strategy predicts $6 billion in revenue and ... - SmartCompany - May 6th, 2023 [May 6th, 2023]
- Nature's Quantum Secret: Link Discovered Between Photosynthesis ... - SciTechDaily - May 6th, 2023 [May 6th, 2023]
- Two ERC proof of concept grants for the University of Bonn - EurekAlert - May 6th, 2023 [May 6th, 2023]