Everything will be alright. What if B is also associated with a quantum object that is in a superposition of two locations? Then the quantum state of A is now divided in two different ways depending on the possible locations of B. Because determining the quantum state of B determines the state of A, A and B are now entangled.
In the above example, two of the best properties of a quantum system—superposition and entanglement—depend on the frame of reference. “The main message is that a lot of the properties that we think are very important, and are in a way absolute, relational or relative,” said Anne-Catherine de la HametteCoauthor of recent paper.
Even the sequence of events succumbs to the rigidity of the quantum reference frame. For example, from one reference frame, we can observe the click of a detector occurring at a certain time. But from a different reference frame, the click may end up in a superposition of some other event occurring before and after. Whether you see the click as occurring at a particular time or in a superposition of different sequences of events depends on the choice of reference frame.
first step towards gravity
Researchers hope to use these changing quantum perspectives to understand the mysterious nature of gravity. Einstein's general relativity, which is the classical theory of gravity, says that gravity is the warping of the fabric of space-time by a massive object. But how will space-time be distorted if the object itself is in a superposition of two locations? “It's very hard to answer this with normal quantum physics and gravity,” said Victoria CaballeA researcher in Bruckner's group and co-author of the new paper.
However, switch to a reference frame whose origin is in a superposition, and the giant object may end up in a fixed location. It has now become possible to calculate its gravitational field. “By finding a convenient quantum reference frame, we can take a problem we cannot solve [and make it] A problem for which we can use standard known physics,” Kable said.
Such perspectives should be useful for change analysis. future experiments The purpose of which is to place extremely small masses in superposition. For example, physicist Chiara Marletto And vlatko weatherall near the university of oxford Proposed Placing two masses in superposition at two places and then studying how this affects their gravitational fields. Increasing efforts to formally describe quantum reference frames can help understand these investigations of the interaction between gravity and quantum theory – an essential step towards a theory of quantum gravity.