31 Matching Annotations
  1. Jan 2021
    1. New Quantum Algorithms Finally Crack Nonlinear Equations
      • We can’t predict the weather, among many other complex issues, because computers still can’t solve nonlinear equations.
      • But this might change soon, as two different research teams created algorithms that can be used for nonlinear modelling on quantum computers.
      • Their techniques still need refining, and won’t be real-world ready for years, but these studies are another stepping stone towards truly useful quantum algorithms.
  2. Oct 2020
    1. The graphs of ground state confinement energy againstsize (radius) for zinc sulfide nanoparticles in Figure 14 showthe dependence of confinement on the size of quantum dots.The result shows that ground state confinement energy is

      Las graficas de la energía de confinamiento en su estado fundamental en contra del tamaño (radio) por nanopartículas de sulfato de zinc en la Figura 14 muestran la dependencia de confinamiento en el tamaño de los puntos quánticos. El resultado muestra que el estado fundamental de energía en confinamiento es inversamente proporciona al tamaño (radio). Por lo tanto, cuando uno incrementa su radio (tamaño) la energía de confinamiento decrece pero nunca llega a cero. Eso es, el energía mas baja posible para el punto quántica de muestra no es cero. El confinamiento comienza cuando el radio del punto cuántico de muestra es comparable o del orden del radio exciton de Bohr.

    1. The notion that counting more shapes in the sky will reveal more details of the Big Bang is implied in a central principle of quantum physics known as “unitarity.” Unitarity dictates that the probabilities of all possible quantum states of the universe must add up to one, now and forever; thus, information, which is stored in quantum states, can never be lost — only scrambled. This means that all information about the birth of the cosmos remains encoded in its present state, and the more precisely cosmologists know the latter, the more they can learn about the former.
  3. Jul 2020
  4. Jun 2020
  5. May 2020
    1. quantum blockchain

      Do they really use a quantum blockchain? What exactly do they mean by that? Probably just a buzzword they're using to attract interest but aren't actually meaning literally.

    1. A quantum blockchain, the pair suggests, would take advantage of entanglement, which in most cases, applies to situations regarding space. But it could also be useful for situations involving time, such as blockchains. In such a blockchain, the pair explains, transaction records could be represented by pairs of entangled photons linked in chronological order. When transfers take place, photons would be created and absorbed by the hubs that comprise a network. But since entangled photons are linked across time, they can be caused to have never existed at the same time.
  6. Feb 2020
  7. Jan 2020
    1. ​=(α∣0⟩+β∣1⟩)(γ∣0⟩+δ∣1⟩)=αγ∣00⟩+αδ∣01⟩+βγ∣10⟩+βδ∣11⟩.​

      Might be the answer to an above inquiry.

    2. we apply a Hadamard gate

      What is the method to evaluate whether the output of a Hadamard gate should invert the bottom qubit or not?

      is (0 + 1) / sqrt 2 high or low?

      I'm missing something fundamental here.

    3. equal

      Frustrating wording here for me... Why is the word "equal" here at all. Doesn't seem to clarify anything.

    4. quantum teleportation

      I was thinking yesterday that "quantum" anything is both much more exciting and much less exciting than we've been led to believe by "Pop Science".

      It seems to boil down so far to some fancy linear algebra. I'm sure time will prove me a fool for thinking this, but just want to jot my thoughts down here.

    5. the

      For Computer Scientists, Microsoft put together a primer to Quantum Computing for us here: https://www.youtube.com/watch?v=F_Riqjdh2oM

      I could understand some of it (through 40m), but think this series of articles will help immensely and I'll return to it after.

    6. What does it mean for a matrix UUU to be unitary? It’s easiest to answer this question algebraically, where it simply means that U†U=IU^\dagger U = IU†U=I, that is, the adjoint of UUU, denoted U†U^\daggerU†, times UUU, is equal to the identity matrix. That adjoint is, recall, the complex transpose of UUU:

      Starting to get a little bit more into linear algebra / complex numbers. I'd like to see this happen more gradually as I haven't used any of this since college.

  8. Jul 2019
    1. unitary operator is a surjective bounded operator

      Why must unitary operator only be surjective? Why not bijective?

  9. Mar 2019
    1. Special Complexity Zoo Exhibit: Classes of Quantum States and Probability Distributions 24 classes and counting! A whole new phylum of the Complexity kingdom has recently been identified. This phylum consists of classes, not of problems or languages, but of quantum states and probability distributions. Well, actually, infinite families of states and distributions, one for each number of bits n. Admittedly, computer scientists have been talking about the complexity of sampling from probability distributions for years, but they haven't tended to organize those distributions into classes designated by inscrutable sequences of capital letters. This needs to change.
  10. Jan 2019
    1. The new experiment shows that, in a quantum world, two people can end up disagreeing about a seemingly irrefutable result, such as the outcome of a coin toss, suggesting something is amiss with the assumptions we make about quantum reality.
    2. Frauchiger and Renner came up with their thought experiment, which is an extension of something the physicist Eugene Wigner first dreamed up in the 1960s.
  11. Nov 2018
  12. Aug 2018
    1. Hegel believed that history culminated in an absolute moment - a moment in which a final, rational form of society and state became victorious.

      and probably not a bad outcome in an earlier era that thought of things in terms of clockwork and lacked the ideas of quantum theory and its attendant uncertainties.

  13. May 2018
  14. Apr 2018
    1. “We often discussed his notions on objective reality. I recall that during one walk Einstein suddenly stopped, turned to me and asked whether I really believed that the moon exists only when I look at it.”
  15. Mar 2018
  16. Feb 2018
  17. Dec 2015
    1. this week’s announcement by Google that a machine made by a Canadian company, D-Wave Systems, which is marketed as “the world’s first commercial quantum computer”, had shown spectacular speed gains over conventional computers. “For a specific, carefully crafted proof-of-concept problem,” Google’s Hartmut Neven reported, “we achieved a 100-million-fold speed-up.”
  18. Oct 2015
    1. the strongest evidence yet to support the most fundamental claims of the theory of quantum mechanics about the existence of an odd world formed by a fabric of subatomic particles, where matter does not take form until it is observed and time runs backward as well as forward.
  19. Feb 2014
    1. The mathematics of almost all eigenvalue problems encountered in wave physics is essentially the same, but the richest source of such problems is quantum mechanics, where the eigenvalues are the energies of stationary states ("levels"), rather than frequencies as in acoustics or optics, and the operator is the hamiltonian.