The researchers have successfully simulated quantum computations with an error correction code known as the Gottesman-Kitaev-Preskill (GKP) code. This code is commonly used in leading implementations of quantum computers and allows for the correction of errors without destroying the quantum information.

The method developed by the researchers consists of an algorithm capable of simulating quantum computations using a bosonic code, specifically the GKP code. This achievement has been deemed impossible until now due to the immense complexity of quantum computations.

“We have discovered a way to simulate a specific type of quantum computation where previous methods have not been effective,” says Cameron Calcluth, PhD in Applied Quantum Physics at Chalmers and first author of the study published in Physical Review Letters. “This means that we can now simulate quantum computations with an error correction code used for fault tolerance, which is crucial for being able to build better and more robust quantum computers in the future.”

The researchers’ breakthrough has far-reaching implications for the development of stable and scalable quantum computers, which are essential for solving complex problems in various fields. The new method will enable researchers to test and validate a quantum computer’s calculations more reliably, paving the way for the creation of truly reliable quantum computers.

The article Classical simulation of circuits with realistic odd-dimensional Gottesman-Kitaev-Preskill states has been published in Physical Review Letters. The authors are Cameron Calcluth, Giulia Ferrini, Oliver Hahn, Juani Bermejo-Vega, and Alessandro Ferraro.

Quantum computers have been touted as potential game-changers for computation, medicine, coding, and material discovery – but only when they truly function. One major obstacle has been noise or errors produced during computations on a quantum machine, making them less powerful than classical computers – until recently.

Daniel Lidar, holder of the Viterbi Professorship in Engineering and Professor of Electrical & Computing Engineering at USC Viterbi School of Engineering, has made significant strides in quantum error correction. In a recent study with collaborators at USC and Johns Hopkins, he demonstrated a quantum exponential scaling advantage using two 127-qubit IBM Quantum Eagle processor-powered quantum computers over the cloud.

The key milestone for quantum computing, Lidar says, is to demonstrate that we can execute entire algorithms with a scaling speedup relative to ordinary “classical” computers. An exponential speedup means that as you increase a problem’s size by including more variables, the gap between the quantum and classical performance keeps growing – roughly doubling for every additional variable.

Lidar clarifies that this type of speedup is unconditional, meaning it doesn’t rely on unproven assumptions. Prior speedup claims required assuming there was no better classical algorithm against which to benchmark the quantum algorithm. This study used an algorithm modified for the quantum computer to solve a variation of “Simon’s problem,” an early example of quantum algorithms that can solve tasks exponentially faster than any classical counterpart, unconditionally.

Simon’s problem involves finding a hidden repeating pattern in a mathematical function and is considered the precursor to Shor’s factoring algorithm, which can be used to break codes. Quantum players can win this game exponentially faster than classical players.

The team achieved their exponential speedup by squeezing every ounce of performance from the hardware: shorter circuits, smarter pulse sequences, and statistical error mitigation. They limited data input, compressed quantum logic operations using transpilation, applied dynamical decoupling to detach qubits from noise, and used measurement error mitigation to correct errors left over after dynamical decoupling.

Lidar says that this result shows today’s quantum computers firmly lie on the side of a scaling quantum advantage. The performance separation cannot be reversed because the exponential speedup is unconditional – making it increasingly difficult to dispute. Next steps include demonstrating practical real-world applications, reducing noise and decoherence in ever larger quantum computers, and addressing the lack of oracle-based speedups.

Quantum computers have long been touted as revolutionary machines capable of solving complex problems that stymie conventional supercomputers. However, their full potential has been hindered by the limitations of qubit amplifiers – essential components required to read and interpret quantum information. Researchers at Chalmers University of Technology in Sweden have taken a significant step forward with the development of an ultra-efficient amplifier that reduces power consumption by 90%, paving the way for more powerful quantum computers with enhanced performance.

The new amplifier is pulse-operated, meaning it’s activated only when needed to amplify qubit signals, minimizing heat generation and decoherence. This innovation has far-reaching implications for scaling up quantum computers, as larger systems require more amplifiers, leading to increased power consumption and decreased accuracy. The Chalmers team’s breakthrough offers a solution to this challenge, enabling the development of more accurate readout systems for future generations of quantum computers.

One of the key challenges in developing pulse-operated amplifiers is ensuring they respond quickly enough to keep pace with qubit readout. To address this, the researchers employed genetic programming to develop a smart control system that enables rapid response times – just 35 nanoseconds. This achievement has significant implications for the future of quantum computing, as it paves the way for more accurate and powerful calculations.

The new amplifier was developed in collaboration with industry partners Low Noise Factory AB and utilizes the expertise of researchers at Chalmers’ Terahertz and Millimeter Wave Technology Laboratory. The study, published in IEEE Transactions on Microwave Theory and Techniques, demonstrates a novel approach to developing ultra-efficient amplifiers for qubit readout and offers promising prospects for future research.

In conclusion, the development of this highly efficient amplifier represents a significant leap forward for quantum computing. By reducing power consumption by 90%, researchers have opened doors to more powerful and accurate calculations, unlocking new possibilities in fields such as drug development, encryption, AI, and logistics. As the field continues to evolve, it will be exciting to see how this innovation shapes the future of quantum computing.