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Quantum Class 14, Thu 2022-10-20

1 Followup on free-ranging discussion time, 3

1.1 Accreditation

Example of students who don't understand accreditation being tricked:

  1. In Florida, non-accredited colleges say that their credits "may" transfer to the prestigious state colleges.

  2. The credits do not transfer. There was no quality control or other standards for those credits.

1.2 Compiling quantum computer programs

  1. Executing a Pascal-like program to an actual quantum computer has several steps.

  2. The actual quantum computer has physical qbits.

  3. Some (but usually not most) pairs of qbits are connected; see the graph description of the quantum computer.

  4. A 2-qbit operation like CCNOT can happen only on a connected pair.

  5. Not all the quantum operations that we've seen have physical realizations. Which do depends on the hardware. IBM is different from IONQ.

  6. The user writing the program is properly unaware of any of this. S/he just uses meaningful variable names and useful ops.

  7. Maybe s/he draws a qiskit diagram, which is basically equivalent to the program.

  8. The compiler has to:

    1. Translate unrealizable operations into sequences of realizable operations.

    2. Decide how to optimally assign the variables to actual qbits.

    3. Remember that operations can occur only between adjacent qbits, so try to assign qbits to maximize this adjacency.

    4. To operate on other pairs of qbits, add swap operations to make them adjacent.

    5. These (and all) operations are noisy and take time.

    6. The quantum computer has a limit (the quantum volume) on how much it can do before accumulated noise etc destroys the results.

    7. Look for opportunities to optimize and reduce pairs of consecutive operations. This happens a lot.

  9. Qiskit and its competitors do all this.

  10. This is reminiscent of compiling onto a classical machine with limited registers.

  11. Optimal solutions are NP, but good enough solutions are possible.

  12. Someone is probably using a quantum computer to compile.

1.3 Being a grad student here at RPI

How might we help?

2 Student presentations, round 2

Pick your date (choices: next Mon or Thurs) and announce your topic here:

When signing up, use enough of your name(s) that I can recognize you, plus your topic.

3 News

  1. The Nobel Prize in Physics 2022

  2. New research suggests our brains use quantum computation


    Note Malta.



    can be interesting


    has little traffic

4 Optimization problems doable with D-wave

  1. Max cut

  2. VLSI Circuit opt

  3. Spin glass min energy

  4. A Quantum Annealing Approach for Fault Detection and Diagnosis of Graph-Based Systems


5 D-Wave

We'll go thru