Verification of Quantum Computations and Quantum Supremacy

Lead Research Organisation: University of Warwick
Department Name: Physics


Quantum computers hold the promise to decidedly increase our computing capacity, providing a huge speed-up in the solution of a certain class of problems which are believed to be intractable by classical devices. An example of that is represented by the simulation of microscopic systems,
which is one of the central problems in modern science and has a wide range of applications - from drug design to nuclear physics to quantum
chemistry and biology. For instance, while there is no known classical algorithm able to efficiently simulate microscopic systems, it is widely
believed that "quantum simulators" will someday be able to simulate interesting microscopic systems. Since many experimental challenges still
make the road to a universal quantum computer a hard one, intermediate non-universal machines are nowadays regarded with great interest and
might possibly be built in the following decades. However, a fundamental question concerning their "certification" arises: how can a classical
observer certify the correctness of the outcome of a quantum simulator? How can he get confidence about the correct functioning of the machine,
if the outcome he obtains has never been obtained by means of a classical device?
My PhD project is focused on the study and the development of protocols for the certification of quantum simulators. In particular, I will initially
try to optimise already existing protocols whose objective is to give an answer to the questions addressed above, while I will subsequently try to
adapt them to apply in realistic settings, e.g. in an actual experiment with the presence of noise.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509711/1 01/10/2016 30/09/2021
1953497 Studentship EP/N509711/1 03/10/2016 31/03/2020 Samuele Ferracin
Description Quantum computers promise to boost our computing capabilities well beyond current ones. However, the existing prototypes of quantum computers are afflicted by high levels of internal noise, which may potentially disrupts their outputs. Thus, any fruitful use of current quantum computers relies on the capability of checking that they return the correct outputs.

The outputs of the existing prototypes of quantum computers are checked by simulating the computation of interest on a supercomputer. This is practical for the present, however it will soon become unfeasible (simulating quantum computations on supercomputers requires time and memory that increase exponentially with the size of the computation).

In our research we have developed alternative protocols to check the outputs of quantum computers. Our protocols are practical for current quantum computers, moreover they are scalable for future applications. They will thus play an important role in future quantum computers.
Exploitation Route Our research has attracted the attention of other research groups and private companies interested in testing their own quantum computers. We are currently collaborating with a few of these groups to demonstrate our most promising protocols on real quantum computers.
Notably, one of our protocols has been included in IBM's Qiskit Project on Github for use on IBM's quantum computers.
Sectors Digital/Communication/Information Technologies (including Software)