Results · Line of research

The price of perfection

What it costs a finite quantum system to approach a perfect strategy it can never reach, and whether that cost can be computed.

Nine works in nineteen archived versions · latest release

The question

The papersin reading order, with what each settled

  1. The uncomputable price of precision

    Seth Douglas and Nidhal Mghirbi · version 4.0.0 · · 119 pages

    For finite rational constraint-system games of quantum value one, the positive exponents of the least local dimension needed near perfect play are exactly the positive Δ20 reals, with matched distillable-entanglement realizations; the lower and upper exponent pairs are exactly the (Σ20,Π20) pairs.

    The paperPDFDOICode

  2. Uncomputable critical exponents

    Seth Douglas and Nidhal Mghirbi · version 2.1.0 · · 64 pages

    Translation-invariant nearest-neighbour quantum Hamiltonians whose critical gap exponents are exactly the nonnegative Δ30 reals, already in two dimensions; and robust laws of noisy media that no effective inquiry can learn beyond Δ20.

    The paperPDFDOICode

  3. A beginning is worth one limit: robust unlearnable laws in noisy cellular automata

    Seth Douglas and Nidhal Mghirbi · version 1.0.0 · · 19 pages

    At equal depth, a computable law of a cellular automaton that has a beginning reaches one arithmetical level above any law on which its stationary states agree; at depth one, a rule started from cloned uniform noise realizes every Δ30 value in [0,1] as a robust law.

    The paperPDFDOICode

  4. An explicit nonlocal game of quantum value one that needs exponential entanglement

    Nidhal Mghirbi and Seth Douglas · version 1.1.0 · · 93 pages

    A binary linear system game with 1687 equations in 1993 variables, of quantum value one, in which winning with probability 1−ε needs entanglement entropy ε−1+o(1), hence local dimension exp⁡(ε−1+o(1)); the exponent is sharp.

    The paperPDFDOICode

  5. The price of precision: usable entanglement in nonlocal games and the geometry of groups

    Seth Douglas and Nidhal Mghirbi · version 1.1.0 · · 160 pages

    For the game classes treated, the entanglement demand near perfect play diverges exactly when no finite-dimensional strategy is perfect; bounded demand is undecidable among games of value one; and the geometry of groups gives logarithmic, almost inverse-loss and intermediate laws.

    The paperPDFDOICode

  6. The price of unreachable perfection: dimension laws at every regular scale

    Seth Douglas and Nidhal Mghirbi · version 1.0.1 · · 24 pages

    The growth of the least dimension can be prescribed at every regular scale, not only along power laws. At every asymptotically flat scale the normalized endpoints are exactly the (Σ20,Π20) pairs, and a computable target can still lie outside every game’s profile.

    The paperPDFDOICode

  7. Matter that pays the price of perfection

    Seth Douglas and Nidhal Mghirbi · version 1.0.0 · · 27 pages

    Gapped translation-invariant lattices whose entanglement has any prescribed limit-computable logarithmic coefficient, and a referee cell that converts low energy into strategies for a nonlocal game. The game-driven material theorem is stated conditionally.

    The paperPDFDOICode

  8. Perfect play in a binary-scoring nonlocal game requires infinite dimension but only finite energy

    Seth Douglas and Nidhal Mghirbi · version 2.0.0 · · 39 pages

    A game with ten and eleven questions and at most six answers is won perfectly by an infinite-dimensional strategy and by no finite one, with dimension profile 10log2⁡(1/ε)+O(log⁡log⁡(1/ε)). Perfect play needs only finite energy: 275/18 quanta per oscillator at best.

    The paperPDFDOICode

  9. The heat price of precision

    Seth Douglas and Nidhal Mghirbi · version 1.0.0 · · 21 pages

    For games whose usable-entanglement demand diverges, resetting locally before communicating forces divergent work, while bringing the systems back together before reset keeps the operating work bounded.

    The paperPDFDOICode

Posed by othersproblems printed by others that this line takes up

What is openfive questions