Jan 21, 2020 01:52 AM
(This post was last modified: Jan 21, 2020 01:58 AM by C C.)
https://www.nature.com/articles/d41586-020-00120-6
INTRO: Albert Einstein famously said that quantum mechanics should allow two objects to affect each other’s behaviour instantly across vast distances, something he dubbed “spooky action at a distance”. Decades after his death, experiments confirmed this. But, to this day, it remains unclear exactly how much coordination nature allows between distant objects. Now, five researchers say they have solved a theoretical problem that shows that the answer is, in principle, unknowable.
The team’s proof, presented in a 165-page paper, was posted on on the arXiv preprint repository on 14 January, and has yet to be peer reviewed. If it holds up, it will solve in one fell swoop a number of related problems in pure mathematics, quantum mechanics and a branch of computer science known as complexity theory. In particular, it will answer a mathematical question that has been unsolved for more than 40 years.
If their proof checks out, “it’s a super-beautiful result” says Stephanie Wehner, a theoretical quantum physicist at Delft University of Technology in the Netherlands. At the heart of the paper is a proof of a theorem in complexity theory, which is concerned with efficiency of algorithms. Earlier studies had shown this problem to be mathematically equivalent to the question of spooky action at a distance — also known as quantum entanglement3.
The theorem concerns a game-theory problem, with a team of two players who are able to coordinate their actions through quantum entanglement, even though they are not allowed to talk to each other. This enables both players to ‘win’ much more often than they would without quantum entanglement. But it is intrinsically impossible for the two players to calculate an optimal strategy, the authors show. This implies that it is impossible to calculate how much coordination they could theoretically achieve. “There is no algorithm that is going to tell you what is the maximal violation you can get in quantum mechanics,” says co-author Thomas Vidick at the California Institute of Technology in Pasadena.
[...] “I’m shitting bricks here,” commented another physicist, Mateus Araújo ... “I never thought I’d see this problem being solved in my lifetime." ... (MORE - details)
INTRO: Albert Einstein famously said that quantum mechanics should allow two objects to affect each other’s behaviour instantly across vast distances, something he dubbed “spooky action at a distance”. Decades after his death, experiments confirmed this. But, to this day, it remains unclear exactly how much coordination nature allows between distant objects. Now, five researchers say they have solved a theoretical problem that shows that the answer is, in principle, unknowable.
The team’s proof, presented in a 165-page paper, was posted on on the arXiv preprint repository on 14 January, and has yet to be peer reviewed. If it holds up, it will solve in one fell swoop a number of related problems in pure mathematics, quantum mechanics and a branch of computer science known as complexity theory. In particular, it will answer a mathematical question that has been unsolved for more than 40 years.
If their proof checks out, “it’s a super-beautiful result” says Stephanie Wehner, a theoretical quantum physicist at Delft University of Technology in the Netherlands. At the heart of the paper is a proof of a theorem in complexity theory, which is concerned with efficiency of algorithms. Earlier studies had shown this problem to be mathematically equivalent to the question of spooky action at a distance — also known as quantum entanglement3.
The theorem concerns a game-theory problem, with a team of two players who are able to coordinate their actions through quantum entanglement, even though they are not allowed to talk to each other. This enables both players to ‘win’ much more often than they would without quantum entanglement. But it is intrinsically impossible for the two players to calculate an optimal strategy, the authors show. This implies that it is impossible to calculate how much coordination they could theoretically achieve. “There is no algorithm that is going to tell you what is the maximal violation you can get in quantum mechanics,” says co-author Thomas Vidick at the California Institute of Technology in Pasadena.
[...] “I’m shitting bricks here,” commented another physicist, Mateus Araújo ... “I never thought I’d see this problem being solved in my lifetime." ... (MORE - details)