Displaying items by tag: Quantum Advantage

Qu&Co comments on this publication:

Quantum computational supremacy (QCS) arguments have been provided to demonstrate that quantum computers will soon outperform classical computers in a variety of algorithms. However, in order to truly prove supremacy, several strict measures need to be taken: an appropriate algorithm must be selected, a quantum device to run the algorithm must be designed, the ability to verify the results of the calculations must be considered and a complexity theory that supports the claim that a classical computer would be unable to run such an algorithm should be provided. Quantum circuits running on quantum computing chips that are currently experimentally realized might still be able to be simulated in highly parallelized state-of-the-art classical supercomputers, therefore one can only make conjectures about QCS at the moment. Typically, classical simulation of certain families of quantum circuits require scaling that is worse than any polynomial in the size of the circuit, which prevents us from calculating exactly the number of qubits these quantum circuits must have for their classical simulation to be intractable on modern classical supercomputers.

In this paper, three refined fine-grained conjectures about quantum supremacy are provided and it is calculated that 208 qubits and 500 gates for Instantaneous Quantum Polynomial-Time (IQP) circuits, 420 qubits and 500 constraints for Approximate Optimization Algorithm (QAOA) circuits and 98 photons and 500 optical elements are sufficient. Although noise in current quantum devices cannot be fully approximated, a lower bound on the runtime of all three algorithms for any multiplicative-error classical simulation is provided.

This paper provides a concrete estimation on the number of qubits required for three algorithms that have gained a lot of attention during the NISQ era. While the orginal work stems from 2018,  the number of qubits required has been recalculated in the newest version of this paper, which provides a good indication of how fidelity of quantum chips has been improved in the last two years, as well as the latest understanding in complexity and the on-going evolution in classical competition.

Published in Blog

Qu&Co comments on this publication:

Recently some contributors to a paper describing a quantum-supremacy experiment inadvertently posted an older version of this paper online, which was quickly picked-up by the popular press resulting in a flurry of (in many cases) unfounded claims about the progress of quantum-computing. We believe that it is important for people interested in this topic to inform themselves through reading a balanced opinion from someone who is an expert in this field. Therefore we kindly refer to Scott Aaronson's excellent blogpost on this matter. 

Published in Blog
Tagged under

Qu&Co comments on this publication:

In this paper, Neill et al. (Google/UCSB), present experimental results for their 9 transmon (gmon) qubit device and illustrate that these experiments form a blueprint for demonstrating quantum supremacy on their next-generation (50 qubit) system. By individually tuning the qubit parameters, they are able to generate thousands of unique Hamiltonian evolutions and probe the output probabilities. The measured probabilities obey a universal distribution, consistent with uniformly sampling the full Hilbert-space. As the number of qubits in the algorithm is varied, the system continues to explore the exponentially growing number of states. They also compare the measurement results with the expected behavior and show that the algorithm can be implemented with high fidelity.

Published in Blog
Tagged under

Qu&Co comments on this publication:

In this article Boixo et al. (Google/UCSB) present their proposed quantum supremacy experiment. Their proposal uses the task of sampling from the output distributions of (pseudo-) random quantum circuits, which, classically, requires a direct numerical simulation of the circuit, with computational cost exponential in the number of qubits.. They estimate that in such experiment, quantum supremacy can be achieved in the near-term with approximately 50 superconducting qubits. Furthermore they introduce cross entropy as a practical test of quantum supremacy.

Published in Blog
Tagged under

What's Interesting?

How can we help you?

Invalid Input

Invalid Input

Invalid Input

Invalid Input

Invalid Input

Invalid Input

Copyright © Qu & Co BV
close