4/20/2023 0 Comments Harlow quantum error correction![]() In other words, a weak measurement is one in which the coupling between the measuring device and the observable to be measured is so weak that the uncertainty in a single measurement is large compared with the separation between the eigenvalues of the observable. The Weak Measurement in Quantum Mechanics – 2012Įxcerpt: The basic idea of the weak measurement is that the interaction (or disturbance) between the measuring apparatus and the observed system or particle is so weak, that the wave function does not collapse but continues on unchanged. The trick to not collapsing the wave function is to only collect partial ‘fuzzy’ information with a weak measurement so as to leave the wave function in an indeterminate ‘uncertain’ state. In a purposeless universe, what are the quantum-level errors that these correction processes are trying to address? The second question is that to correct an error you have to know in advance what an error is in a given system. They have to know the actual quantum states of these entangled particles before they can know if there is an error to be corrected. These “gates” are measuring the quantum states of these particles. When there’s no error (meaning the qubits are in the state |000? + |111?), the parity-measuring gates determine that both the first and second and the first and third qubits are always the same.Īs has been discussed many times here, observation or measurement of quantum particles “collapses” them from many possible but indeterminate states into a single actual state. One gate checks the “parity” of the first and second physical qubit - whether they’re the same or different - and the other gate checks the parity of the first and third. The qubits can be fed through two gates in a quantum circuit. What’s more, these schemes must detect and correct errors without directly measuring the qubits, since measurements collapse qubits’ coexisting possibilities into definite realities See also: What becomes of science when the evidence does not matter?įor quantum computers to work, scientists must find schemes for protecting information even when individual qubits get corrupted. They certainly make it sound as though our universe is designed. And the right way is to build a quantum error-correcting code.” Natalie Wolchover, “ How Space and Time Could Be a Quantum Error-Correcting Code” at Quanta “If you want to weave space-time together out of little pieces, you have to entangle them in the right way. “It’s really entanglement which is holding the space together,” he said. ![]() The paper has triggered a wave of activity in the quantum gravity community, and new quantum error-correcting codes have been discovered that capture more properties of space-time. They conjectured in the Journal of High Energy Physics that space-time itself is a code - in anti-de Sitter (AdS) universes, at least. Ahmed Almheiri, Xi Dong and Daniel Harlow did calculations suggesting that this holographic “emergence” of space-time works just like a quantum error-correcting code. ![]() The bendy fabric of space-time in the interior of the universe is a projection that emerges from entangled quantum particles living on its outer boundary. They were working in physicists’ theoretical playground of choice: a toy universe called “anti-de Sitter space” that works like a hologram. That year - 2014 - three young quantum gravity researchers came to an astonishing realization. (A ball tossed into the air travels along a straight line through space-time, which itself bends back toward Earth.) But powerful as Einstein’s theory is, physicists believe gravity must have a deeper, quantum origin from which the semblance of a space-time fabric somehow emerges. In Albert Einstein’s general theory of relativity, gravity is defined as the fabric of space and time - or “space-time” - bending around massive objects. But some argue, the same codes used to prevent errors in quantum computers might give space-time “its intrinsic robustness”:īut in the dogged pursuit of these codes over the past quarter-century, a funny thing happened in 2014, when physicists found evidence of a deep connection between quantum error correction and the nature of space, time and gravity. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |