{"id":50563,"date":"2025-08-06T22:43:12","date_gmt":"2025-08-06T22:43:12","guid":{"rendered":"https:\/\/www.newsbeep.com\/ca\/50563\/"},"modified":"2025-08-06T22:43:12","modified_gmt":"2025-08-06T22:43:12","slug":"quantum-breakthrough-enables-scientists-to-reverse-the-flow-of-time","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ca\/50563\/","title":{"rendered":"Quantum breakthrough enables scientists to reverse the flow of time"},"content":{"rendered":"

In the world of quantum physics, the rules that govern reality behave in ways that challenge what we think we know. Particles can be in two places at once. Actions on one particle can instantly affect another, even across vast distances. Teleportation<\/a> isn\u2019t science fiction\u2014it\u2019s part of how the universe really works at the tiniest level. Now, researchers have added something even stranger to the mix: quantum time travel.<\/p>\n

Not time machines in the classic sci-fi sense. Instead, this is a breakthrough in controlling time within quantum systems\u2014particles so small that regular physics barely applies. A group of scientists from Austria has shown that you can speed up, slow down, and even reverse the “age” of these particles, effectively rewinding time for them.<\/p>\n

The Quantum Switch That Changes Everything<\/p>\n

At the center of this work is a clever device called a quantum switch. Think of it as a remote control for quantum particles<\/a>. While traditional physics moves like a movie in a theater\u2014playing from start to finish no matter what\u2014quantum systems behave more like watching a movie at home, where you can fast-forward, rewind, or skip scenes altogether.<\/p>\n

Researchers from the Austrian Academy of Sciences (\u00d6AW), which houses the laboratories of the Institute for Quantum Optics and Quantum Information (IQOQI). (CREDIT: \u00d6AW) <\/p>\n

Miguel Navascu\u00e9s from the Austrian Academy of Sciences<\/a> compared it to having control over time itself. \u201cWe can rewind to a previous scene or skip several scenes ahead,\u201d he said. This is not just theory. Together with University of Vienna<\/a> physicist Philip Walther, Navascu\u00e9s and colleagues used photons\u2014particles of light\u2014to test their ideas.<\/p>\n

Using crystals and a setup based on the quantum switch, they sent a photon on a journey, then used the switch to bring it back to the state it was in before the trip began. This may sound simple, but in the world of quantum mechanics, it’s revolutionary. Normally, just observing a quantum system causes it to change. That\u2019s what makes this discovery so remarkable: they were able to rewind the system without knowing anything about what happened to it.<\/p>\n

Reversing Time with No Clue What Happened<\/p>\n

This method, called a “rewind protocol,” lets any quantum particle<\/a>\u2014like an electron or photon\u2014go back to a previous state, even if the experimenter doesn\u2019t know what that state was or how it got there. David Trillo, another researcher from the Austrian team, helped show that the process works in both theory and in the lab.<\/p>\n

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\u201cIt was one of the most difficult experiments we\u2019ve ever built for a single photon,\u201d Walther said. But the result was clear: the photon returned to its original state, like hitting rewind on a video without ever watching it.<\/p>\n

The team also went beyond rewinding. They found that you can fast-forward time, too. \u201cTo make a system age 10 years in one year,\u201d Navascu\u00e9s explained, \u201cyou must get the other nine years from somewhere.\u201d In one experiment, they used ten identical systems. By \u201cstealing\u201d one year of aging from each of the first nine, they gave all nine years to the tenth system, which aged 10 years in just one.<\/p>\n

Rewind Protocol: A New Tool for Quantum Processors<\/p>\n

These discoveries won\u2019t let anyone travel back in time<\/a> or undo mistakes in real life. A human body holds massive amounts of information, and it would take millions of years to rewind even one second of someone\u2019s life. But that\u2019s not the point.<\/p>\n

The goal is to make quantum processors more powerful and reliable. In quantum computers, which store data in tiny, delicate particles, errors can creep in easily. If you could rewind the system and correct the error, you’d save time and energy.<\/p>\n

Experimental setup. A pulsed Ti: sapphire laser pumps a spontaneous parametric down conversion source to generate pairs of single photons in a type-II process using a pp KTP crystal (top left). (CREDIT: Optica) <\/p>\n

\u201cWe are convinced that it has technological applications,\u201d said Walther. \u201cFor example, a rewind protocol in quantum processors can be used to reverse unwanted errors or developments.\u201d Other team members added that future versions could be built using systems beyond just light, and even expanded to more complex setups.<\/p>\n

Quantum Time Reversal Breaks Classical Limits<\/p>\n

Normally, time only flows forward. This \u201carrow of time,\u201d first described by astronomer Arthur Eddington, follows the second law of thermodynamics<\/a>, which says things naturally become more disordered. But this law is statistical\u2014it applies to big systems, not necessarily the smallest ones.<\/p>\n

In classical physics, it\u2019s possible to reverse some processes using a trick called phase conjugation. But in quantum mechanics, random noise usually gets in the way. That\u2019s why scientists have long wondered: can you reverse time for a quantum system without knowing anything about it?<\/p>\n

Several past studies tried to answer that. But they only worked some of the time and required detailed knowledge of the system or slow, complex procedures. This new protocol is different. It works for any two-level system (known as a qubit), has a high success rate, and runs in real time. That means if you rewind a system by five minutes, it actually takes five minutes.<\/p>\n

Experimental results. (a) Experimental state fidelities. Each bar shows the measured state fidelity averaged over all 50 pairs of U,V, the four different input states, and three independent experimental runs, giving a total of 600 different reconstructed density matrices for each value of n. (CREDIT: Optica) Quantum Operators and the Time Machine Illusion<\/p>\n

At the heart of this method lies a key idea from quantum mechanics: the non-commuting nature of quantum operators. This just means the order in which you apply operations matters, unlike in normal math. Using that principle, the scientists created a setup where the target system evolves in a superposition<\/a>\u2014a mix of different timelines.<\/p>\n

Each timeline includes slight changes caused by known physical interactions. By cleverly interfering these timelines, they guided the particle back to a previous state, no matter what path it took. And if something went wrong, they could try again using error correction, boosting the odds of success.<\/p>\n

The setup used light particles<\/a> manipulated by half- and quarter-wave plates to generate different \u201cHamiltonians\u201d\u2014rules that define how the particle evolves in time. Then, using fast optical switches and the quantum switch, they mixed the time paths together to create the rewind effect.<\/p>\n

Not Just Theory\u2014This Is Real Science<\/p>\n

These results are more than just an idea on paper. The team tested their method on many different quantum processes and reached a rewind accuracy of over 95%. That level of control opens the door to using quantum time reversal in real-world technologies.<\/p>\n

The rewind protocol could help develop better quantum computers<\/a> and new ways to control quantum states in labs. It could even offer insights into how time works in the deepest parts of physics.<\/p>\n

Still, Navascu\u00e9s stays realistic. \u201cIf we could lock a person in a box with zero external influences, it would be theoretically possible [to rewind them],\u201d he said. \u201cBut with our current protocols, the probability of success would be very, very low.\u201d<\/p>\n

In other words, it\u2019s not time travel as you know it\u2014but it\u2019s the closest thing physics has come to bending the clock backward.<\/p>\n

Research findings are available online in the journal Optica<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"In the world of quantum physics, the rules that govern reality behave in ways that challenge what we…\n","protected":false},"author":2,"featured_media":50564,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24],"tags":[49,48,314,66],"class_list":{"0":"post-50563","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-physics","8":"tag-ca","9":"tag-canada","10":"tag-physics","11":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/50563","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/comments?post=50563"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/50563\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media\/50564"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media?parent=50563"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/categories?post=50563"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/tags?post=50563"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}