Cosmology Intelligent Design Physics

We don’t often hear space and time described as a quantum error-correcting code

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This image represents the evolution of the Universe, starting with the Big Bang. The red arrow marks the flow of time.
Big Bang/NASA

But some argue, the same codes used to prevent errors in quantum computers might give space-time “its intrinsic robustness”:

But 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. 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. (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.

That year — 2014 — three young quantum gravity researchers came to an astonishing realization. They were working in physicists’ theoretical playground of choice: a toy universe called “anti-de Sitter space” that works like a hologram. 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. 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. They conjectured in the Journal of High Energy Physics that space-time itself is a code — in anti-de Sitter (AdS) universes, at least. 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. …

“It’s really entanglement which is holding the space together,” he said. “If you want to weave space-time together out of little pieces, you have to entangle them in the right way. 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

They certainly make it sound as though our universe is designed.

See also: What becomes of science when the evidence does not matter?

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2 Replies to “We don’t often hear space and time described as a quantum error-correcting code”

  1. 1
    Seversky says:
    January 5, 2019 at 4:51 pm

    This raises two questions

    First, we are told that:

    For quantum computers to work, scientists must find schemes for protecting information even when individual qubits get corrupted. What’s more, these schemes must detect and correct errors without directly measuring the qubits, since measurements collapse qubits’ coexisting possibilities into definite realities

    Later we are told:

    The qubits can be fed through two gates in a quantum circuit. 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. 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.

    As 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. These “gates” are measuring the quantum states of these particles. They have to know the actual quantum states of these entangled particles before they can know if there is an error to be corrected.

    The second question is that to correct an error you have to know in advance what an error is in a given system. In a purposeless universe, what are the quantum-level errors that these correction processes are trying to address?

  2. 2
    bornagain77 says:
    January 5, 2019 at 8:54 pm

    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.

    The Weak Measurement in Quantum Mechanics – 2012
    Excerpt: 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. 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 [2].
    http://www-f1.ijs.si/~ramsak/s.....cSibka.pdf

    Direct measurement of the quantum wavefunction – June 2011
    Excerpt: The wavefunction is the complex distribution used to completely describe a quantum system, and is central to quantum theory. But despite its fundamental role, it is typically introduced as an abstract element of the theory with no explicit definition.,,, Here we show that the wavefunction can be measured directly by the sequential measurement of two complementary variables of the system. The crux of our method is that the first measurement is performed in a gentle way through weak measurement so as not to invalidate the second. The result is that the real and imaginary components of the wavefunction appear directly on our measurement apparatus. We give an experimental example by directly measuring the transverse spatial wavefunction of a single photon, a task not previously realized by any method.
    http://www.nature.com/nature/j.....10120.html

    Quantum error correction is employed to protect the ‘fragility’ of coherent quantum systems

    Quantum Error Correction for Beginners – 2009
    Excerpt: It was well known from the early developments of this exciting field that the fragility of coherent quantum systems would be a catastrophic obstacle to the development of large scale quantum computers. The introduction of quantum error correction in 1995 showed that active techniques could be employed to mitigate this fatal problem.
    https://arxiv.org/abs/0905.2794

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