0 breakthrough! Quantum computer used for grid computing problem for the first time

Quantum computing has the potential to solve many computational problems with exponential speedup compared to classical computers. As our energy sources increasingly come from wind turbines and photovoltaic systems, the problem of calculating and ensuring grid stability and preventing overloading of cables and transformers becomes more complex. We need new tools to dramatically speed up the computation of power systems: problems such as optimization and safety assessment can all benefit from quantum computing.

Recently, a research team from the Technical University of Denmark (DTU) has performed grid calculations using quantum computers for the first time: using five different quantum computers, applying the HHL quantum algorithm and studying the effect of current noisy quantum hardware on the AC Power Flow Algorithms. accuracy and speed. They performed the same research on 3-bus (3-bus) and 5-bus (5-bus) systems with real quantum computers to identify challenges and open research questions related to the scalability of these algorithms.

On June 16, the preprint version of the related paper "Quantum Computation of Tidal Current Algorithms: Testing on Real Quantum Computers" was published on the arXiv website [1].

Power flow problems have to do with how current is distributed in a meshed grid, and form the basis for a lot of advanced computing in the grid. However, the new algorithm behind the tides problem requires new tools, which cannot be accomplished by today's supercomputers, so the DTU researchers decided to use quantum computers to open up even more possibilities. Although other researchers have tackled similar problems using simulated quantum computers, it has never been done on a real quantum computer.

"We wanted to study how quantum computers can be used to model increasingly complex power systems. So initially we set up a small test case: run on four different quantum computers to make sure our results were valid." Brynjar Sævarsson, who led the experiment, said [2].

Quantum HHL circuit for solving quantum power flow (QPF) of a 3-bus system. Modules in the circuit: Prepare data vector (Load b), Quantum Phase Estimation (QPE), Conditional Rotation (1/x) and Inverse QPE (QPE_dg). Finally, each qubit is measured and the result is stored in a classical 5-bit register, where "meas 0" is the least significant bit and "meas 4" is the most significant bit.

Experimental system for testing quantum power flow (QPF).

Sævarsson's team completed the experiment using a relatively small quantum computer with five qubits available online from IBM. The Tidal application was implemented in IBM's Qiskit (0.34.1), and the 3-bus system was tested on 4 IBM's open quantum computers listed in the table below: ibmq_lima, ibmq_belem, ibmq_quito, and ibmq_bogota.

The quantum computers listed in the table come in different sizes, configurations, and error rates; among them, quantum volume (QV) is a measure of device performance, independent of the underlying technology or the number of qubits.

A quantum computer for testing quantum tides.

After a series of experiments, the team successfully implemented and tested quantum AC power flow applications on a real NISQ quantum computer for the first time; showing that the current hardware is capable of executing power flow algorithms for small test systems.

But scalability is currently a major issue. "Furthermore, quantum computers still generate a lot of noise associated with the calculations, which can affect the accuracy of the results; at the same time, small five-qubit computers are relatively slow. However, our results unquestionably confirm that quantum computers are a kind of Specialized tools, which will be better used in the future to perform some calculations in power systems,” says Sævarsson.

Therefore, in future studies, the researchers will investigate what kinds of computations quantum computers can be used for. The original idea was to hand off complex tasks—including many simultaneous parallel operations, many different values, and computations involving uncertainty—to a quantum computer . This first requires development work by the researchers behind quantum computing in power systems, as well as technical improvements to quantum computers.

Sævarsson said: "The above fields are developing rapidly, and I believe that in the future we will perform calculations in power systems where quantum computers will play an important role. They can do things that ordinary computers can't, which means that we can develop renewable energy-based power systems. The tools needed for a safe and stable power system, and I'm starting the process right now."

IBM and DTU have already worked well together on the project, and the next experiments may be done in closer collaboration with IBM and its latest version of the quantum computer.

Reference link:

[1] https://arxiv.org/abs/2204.14028

[2] https://www.dtu.dk/english/news/all-news/dtu-first-to-use-quantum-computer-for-the-power-grid?id=f1c26196-6390-4065-a0da -0de55b4ab8b1