Talk at the Hacker Dojo in Santa Clara - Nov. 8th, 2019. Video recording available on YouTube: https://www.youtube.com/playlist?list=PL5rRTWhDJLTO8FPLVJ-acHtDEFAlexiL0

1. Google’s - Quantum Supremacy Claim
and the IBM Rebuttal of it!
Are we there yet?
Vesselin G. Gueorguiev
Institute for Advanced Physical Studies
& Ronin Institute
Vesselin G. Gueorguiev Hacker Dojo, Santa Clara - Nov. 8th, 2019 1
Sycamore
Summit at Oak Ridge

2. Outline of the Talk
Ø Is Quantum Supremacy a suitable term?
Ø What did the Google team do?
Ø What is the IBM rebuttal?
Ø Q&A – Discussion.
Vesselin G. Gueorguiev Hacker Dojo, Santa Clara - Nov. 8th, 2019 2

3. Is Quantum Supremacy a suitable term?
• “In quantum computing, quantum supremacy is the potential
ability of devices to solve problems that classical computers
practically cannot.[1] ”
• “…[QC] dates back to Yuri Manin's (1980)[3] and Richard
Feynman's (1981) proposals of quantum computing.[4] ”
Vesselin G. Gueorguiev Hacker Dojo, Santa Clara - Nov. 8th, 2019 3
https://en.wikipedia.org/wiki/Quantum_supremacy

4. What did the Google team do?
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Google Chief Sundar Pichai
Chief Scientists:
John Martinis - Quantum Hardware
Sergio Boixo - Quantum Computing Theory

5. What did the Google team do?
Ø Completed a problem within 200s as compared to
10,000y on a supercomputer;
Ø Programmable Superconducting Processor 54- qubits
processor – Sycamore;
Ø Quality control over the qubits;
² “… improved two-qubit gates with enhanced parallelism that reliably…”
² “… new type of control knob that is able to turn off interactions between
neighboring qubits…”
Ø Sensitive computational benchmark!
Vesselin G. Gueorguiev Hacker Dojo, Santa Clara - Nov. 8th, 2019 5

6. Sycamore Qubits Geometry!
Vesselin G. Gueorguiev Hacker Dojo, Santa Clara - Nov. 8th, 2019 6
Nature | Vol574 | 24OCTOBER2019

7. Google’s process for demonstrating
quantum supremacy
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8. Vesselin G. Gueorguiev Hacker Dojo, Santa Clara - Nov. 8th, 2019 8
Estimate of the equivalent
classical computation time
assuming 1M CPU cores for
quantum supremacy circuits
as a function of the number
of qubits and number of
cycles for the Schrödinger-
Feynman algorithm. The
star shows the estimated
computation time for the
largest experimental
circuits.
the Phase-Space
Diagram

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Nature | Vol574 | 24OCTOBER2019
Linear cross-entropy
benchmarking fidelity function

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Nature | Vol574 | 24OCTOBER2019
Control operations for the
quantum supremacy circuits

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Nature | Vol574 | 24OCTOBER2019

12. Summary - what did Google do.
Ø Completed a problem within 200s as compared to
expected 10,000y on a supercomputer;
Ø The Sycamore quantum computer is fully programmable
and can run general-purpose quantum algorithms;
Ø Sensitive computational benchmark!
Ø Quality control over the qubits.
Ø Certifiable Quantum Random Numbers Generator!
Ø Forward compatible for the implementation of quantum
error-correction!
Vesselin G. Gueorguiev Hacker Dojo, Santa Clara - Nov. 8th, 2019 12

13. What is the IBM rebuttal?
Vesselin G. Gueorguiev Hacker Dojo, Santa Clara - Nov. 8th, 2019 13
https://arxiv.org/abs/1910.09534

14. What is the IBM rebuttal?
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https://arxiv.org/abs/1910.09534
August?

15. What is the IBM rebuttal?
Ø Secondary storage can extend the range of quantum circuits
that can be practically simulated with classical algorithms;
Ø It is possible to simulate the Sycamore circuits with 53 and
54 qubits, with the entanglement pattern ABCDCDAB
quality control over the qubits.
Ø Summit supercomputer at Oak Ridge could simulate it with
high fidelity to arbitrary depth in a matter of days!
Ø Q-circuits can be simulated with high fidelity to arbitrary
depth in a matter of days;
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16. Partitioning Numbers
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17. Vesselin G. Gueorguiev Hacker Dojo, Santa Clara - Nov. 8th, 2019 17
A B C D C D A B

18. Estimated running times
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19. Estimated running times
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20. Estimated running times
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21. Thank You!
Q&A
Open Discussion
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22. Vesselin G. Gueorguiev Hacker Dojo, Santa Clara - Nov. 8th, 2019 22
Nature | Vol574 | 24OCTOBER2019
Pauli and Measurement Errors
“Having found the error rates of the individual gates and readout, we can model the fidelity of a
quantum circuit as the product of the probabilities of error-free operation of all gates and
measurements. Our largest random quantum circuits have 53 qubits, 1,113 single-qubit gates, 430
two-qubit gates, and a measurement on each qubit, for which we predict a total fidelity of 0.2%.”

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