Incoming links: Classical computer
- quantumtech.blog/2023/01/17/quantum-computing-with-neutral-atoms/ OK this one hits it:So we understand that it is truly like the classical computer analog vs digital case.
As Alex Keesling, CEO of QuEra told me, "... whereas in gate-based [digital] quantum computing the focus is on the sequence of the gates, in analog quantum processing it's more about the position of the atoms and where you place them so they can mirror real life problems. We arrange the atoms and define the forces that drive them and then measure the result... so it’s a geometric encoding of the problem itself."
- thequantuminsider.com/2022/06/28/why-analog-neutral-atoms-quantum-computing-is-a-promising-direction-for-early-quantum-advantage on The Quantum Insider useless article mostly by Pasqal
TensorFlow quantum by Masoud Mohseni (2020)
Source. At the timestamp, Masoud gives a thought experiment example of the perhaps simplest to understand analog quantum computer: chained double-slit experiments with carefully calculated distances between slits. Calulating the final propability distribution of that grows exponentially. IBM 2017 beryllium hydride ground state calculation on a quantum computer Updated 2024-12-15 +Created 1970-01-01
TODO what's the largest molecule done on a classical computer?
- www.ibm.com/blogs/research/2017/09/quantum-molecule/
- www.nature.com/articles/nature23879 "Hardware-efficient variational quantum eigensolver for small molecules and quantum magnets"
- www.sciencemag.org/news/2017/09/quantum-computer-simulates-largest-molecule-yet-sparking-hope-future-drug-discoveries
This post-quantum cryptography competition by NIST is a huge milestone of the field.
It was mind blowing when in 2022, after several years of selection, one of the 7 finalists was broken on a classical computer, not even in a quantum computer! news.ycombinator.com/item?id=30466063 | eprint.iacr.org/2022/214 Breaking Rainbow Takes a Weekend on a Laptop by Ward Beullens. Dude announced he had a break a few days before submission: twitter.com/WardBeullens/status/1492780462028300290 On Twitter. He's so young. Epic.
Edit: and then, after the third round, things were a bit unclear, so they made a fourth round with 4 choices out of the 7 from round 3, and in August 2022 one of the four was broken again on a classic CPU!!! OMG: arstechnica.com/information-technology/2022/08/sike-once-a-post-quantum-encryption-contender-is-koed-in-nist-smackdown/
Encryption algorithms that run on classical computers that are expected to be resistant to quantum computers.
This is notably not the case of the dominant 2020 algorithms, RSA and elliptic curve cryptography, which are provably broken by Grover's algorithm.
However, as of 2020, we don't have any proof that any symmetric or public key algorithm is quantum resistant.
Post-quantum cryptography is the very first quantum computing thing at which people have to put money into.
The reason is that attackers would be able to store captured ciphertext, and then retroactively break them once and if quantum computing power becomes available in the future.
There isn't a shade of a doubt that intelligence agencies are actively doing this as of 2020. They must have a database of how interesting a given source is, and then store as much as they can given some ammount of storage budget they have available.
A good way to explain this to quantum computing skeptics is to ask them:Post-quantum cryptography is simply not a choice. It must be done now. Even if the risk is low, the cost would be way too great.
If I told you there is a 5% chance that I will be able to decrypt everything you write online starting today in 10 years. Would you give me a dollar to reduce that chance to 0.5%?
"Quantum interconnect" refers to methods for linking up smaller quantum processors into a larger system.
As of 2024, seemingly few organizations developing quantum hardware had actually integrated multiple chips in interconnects as part of their main current roadmap. But many acknowledged that this would be an essential step towards scalable compuation.
The name "quantum interconnect" is likely partly a throwback to classical computer's "chip interconnect".
Sample usages of the term:
- news.mit.edu/2023/quantum-interconnects-photon-emission-0105
Researchers have demonstrated directional photon emission, the first step toward extensible quantum interconnects
- qpl.ece.ucsb.edu/research/quantum-interconnects
Used e.g. by Oxford Quantum Circuits, www.linkedin.com/in/john-dumbell-627454121/ mentions:
Using LLVM to consume QIR and run optimization, scheduling and then outputting hardware-specific instructions.
Presumably the point of it is to allow simulation in classical computers?
- www.youtube.com/watch?v=1Z9wo2CzJO8 "Schrodinger equation solved numerically in 3D" by Tetsuya Matsuno. 3D hydrogen atom, code may be hidden in some paper, maybe
- www.youtube.com/playlist?list=PLdCdV2GBGyXM0j66zrpDy2aMXr6cgrBJA "Computational Quantum Mechanics" by Let's Code Physics. Uses a 1D trinket.io.
- www.youtube.com/watch?v=BBt8EugN03Q Simulating Quantum Systems [Split Operator Method] by LeiosOS (2018)
- www.youtube.com/watch?v=86x0_-JGlGQ Simulating the Quantum World on a Classical Computer by Garnet Chan (2016) discusses how modeling only local entanglement can make certain simulations feasible
Simulation of the time-dependent Schrodinger equation (JavaScript Animation) by Coding Physics (2019)
Source. Source code: github.com/CodingPhysics/Schroedinger. One dimensional potentials, non-interacting particles. The code is clean, graphics based on github.com/processing/p5.js, and all maths from scratch. Source organization and comments are typical of numerical code, the anonymous author is was likely a Fortran user in the past.
A potential change patch in
sketch.js:- potential: x => 2E+4*Math.pow((4*x - 1)*(4*x - 3),2),
+ potential: x => 4*Math.pow(x - 0.5, 2),Quantum Mechanics 5b - Schrödinger Equation II by ViaScience (2013)
Source. 2D non-interacting particle in a box, description says using Scilab and points to source. Has a double slit simulation.Visualization of Quantum Physics (Quantum Mechanics) by udiprod (2017)
Source. Closed source, but a fantastic visualization and explanation of a 1D free wave packet, including how measurement snaps position to the measured range, position and momentum space and the uncertainty principle.Version of TensorFlow with a Cirq backend that can run in either quantum computers or classical computer simulations, with the goal of potentially speeding up deep learning applications on a quantum computer some day.