Quantum Class 10, Thurs 2020-10-01
Table of contents
1 Student talks next week
are listed in piazza. (I put temporary things there.)
2 D-Wave
https://en.wikipedia.org/wiki/D-Wave_Systems
They make a different type of quantum computer, called a quantum annealer. It is not comparable to quantum gates and circuits like IBM has. D-Wave minimizes a function by testing many solutions in parallel. They have been in the news lately, e.g.,
https://arstechnica.com/science/2020/09/d-wave-releases-its-next-generation-quantum-annealing-chip/
3 Nice intros to qbits
One way that I learn a new topic is to read several different intros.
https://towardsdatascience.com/introduction-to-quantum-programming-a19aa0b923a9?gi=69d861e26d80
https://medium.com/@jonathan_hui/qc-programming-with-quantum-gates-8996b667d256
https://medium.com/@jonathan_hui/qc-programming-with-quantum-gates-2-qubit-operator-871528d136db
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https://www.cl.cam.ac.uk/teaching/0910/QuantComp/notes.pdf
They have a nice description of measurement starting at slide 10.
Each measurement operator has a basis vector set.
The operator represents the qbit as a linear combo of the basis vectors.
Then it projects the qbit onto one of the basis vectors, with probability being the length of that component.
It is possible for two different qbits to measure the same in some basis, but measure different in a different basis.
4 IBM Quantum experience
When you design a circuit here, you don't need to simulate it elsewhere. It shows you the probabilities.
Dual view: you can see and edit both the circuit and the QASM code.
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There are some sample programs in https://github.com/Qiskit/openqasm.git
We'll see how to clone that repository.
We'll use and mod their Deutsch algorithm.
We'll try the example circuits in https://quantum-computing.ibm.com/docs/iqx/example-circuits .
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We'll also see a reversible circuit for (7x mod 15).
That sort of circuit is used in Shor's integer factorization algorithm.
5 Some future classes
Shor's algorithm
How IBM Q works (the hardware).