University of Kwazulu-Natal

Quantum Leap Researchers Achieve First Unconditional Exponential Speed

Bonisiwe Shabane
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quantum leap researchers achieve first unconditional exponential speed

Quantum computing has taken a major step forward with a breakthrough demonstrating an unconditional exponential speedup—a long-awaited milestone in the field. Led by Daniel Lidar, a professor of engineering at the University of Southern California (USC) and a leading expert in quantum error correction, the research was carried out in collaboration with teams from USC... Their findings were published in Physical Review X. Quantum computers have promised transformative capabilities: solving complex equations, designing next-generation medicines, breaking encryption, and discovering new materials. However, one persistent barrier has slowed progress—noise. These small but constant errors disrupt quantum operations, often rendering results less reliable than those from traditional classical computers.

Using IBM’s 127-qubit Eagle quantum processors—remotely accessed via the cloud—Lidar’s team successfully demonstrated an exponential speedup in solving a specific computational task. Unlike previous examples of modest or conditional quantum speedups, this result is exponential and unconditional. That means the performance gap between quantum and classical systems continues to widen as the problem size grows, and the advantage does not rely on any unproven assumptions or theoretical loopholes. The experiment focused on a problem known as Simon’s problem, a theoretical benchmark in quantum computing. This task requires uncovering a hidden repeating pattern within a mathematical function—a type of problem that quantum systems can solve exponentially faster than classical ones. The research team adapted this problem and fine-tuned an algorithm to make it compatible with existing quantum hardware.

Achieving this breakthrough required several innovations to suppress noise and enhance performance: Quantum computers have the potential to speed up computation, help design new medicines, break codes, and discover exotic new materials -- but that's only when they are truly functional. One key thing that gets in the way: noise or the errors that are produced during computations on a quantum machine -- which in fact makes them less powerful than classical computers - until... Daniel Lidar, holder of the Viterbi Professorship in Engineering and Professor of Electrical & Computing Engineering at the USC Viterbi School of Engineering, has been iterating on quantum error correction, and in a new... The paper, "Demonstration of Algorithmic Quantum Speedup for an Abelian Hidden Subgroup Problem," was published in APS flagship journal Physical Review X. "There have previously been demonstrations of more modest types of speedups like a polynomial speedup, says Lidar, who is also the cofounder of Quantum Elements, Inc.

"But an exponential speedup is the most dramatic type of speed up that we expect to see from quantum computers." The key milestone for quantum computing, Lidar says, has always been to demonstrate that we can execute entire algorithms with a scaling speedup relative to ordinary "classical" computers. Interior shot of a quantum computer with an IBM Eagle processor. Credit: IBM For decades, quantum computing has promised to revolutionize the way we solve problems, design drugs, discover new materials, and crack codes. But until now, that promise lived mostly on paper—a thrilling theoretical dream constantly delayed by an inescapable nuisance: noise.

These microscopic whispers of error, generated during the fragile dance of qubits inside a quantum processor, have long kept quantum computers trailing behind their classical cousins. Now, in a remarkable leap forward, a team of researchers led by Daniel Lidar at the University of Southern California has changed the game. They’ve demonstrated, for the first time, an unconditional exponential speedup using real quantum hardware—an achievement once confined to mathematical proofs and theoretical labs. Their study, published in the prestigious journal Physical Review X, marks a pivotal moment in the race toward usable quantum advantage. “This is not a simulation. This is not a prediction.

This is not a speedup that depends on any ‘if’ or ‘maybe’ about classical algorithms,” said Lidar, a professor of engineering, chemistry, and physics at USC and co-founder of Quantum Elements, Inc. “This is a demonstration of quantum performance that scales exponentially better than anything classical computing can offer for this task.” Researchers from USC and Johns Hopkins used two IBM Eagle quantum processors to pull off an unconditional, exponential speedup on a classic “guess-the-pattern” puzzle, proving—without assumptions—that quantum machines can now outpace the best classical... By squeezing extra performance from hardware with shorter circuits, transpilation, dynamical decoupling, and error-mitigation, the team finally crossed a milestone long called the “holy grail” of quantum computing. Quantum computers have long promised to revolutionize technology, with the ability to speed up complex calculations, design new medicines, break modern encryption, and uncover exotic new materials. But there’s been a major obstacle: noise.

That’s the term for all the tiny errors that build up during quantum computations, often making these futuristic machines less effective than even today’s classical computers. A breakthrough led by Daniel Lidar, a professor of engineering at USC and an expert in quantum error correction, has pushed quantum computing past a key milestone. Working with researchers from USC and Johns Hopkins, Lidar’s team demonstrated a powerful exponential speedup using two of IBM’s 127-qubit Eagle quantum processors — all operated remotely through the cloud. Their results were published in the prestigious journal Physical Review X. “There have previously been demonstrations of more modest types of speedups like a polynomial speedup, says Lidar, who is also the cofounder of Quantum Elements, Inc. “But an exponential speedup is the most dramatic type of speed up that we expect to see from quantum computers.”

Conducted on IBM quantum processors, study demonstrates “a promise of quantum computing previously articulated only on paper.” Interior shot of a quantum computer with an IBM Eagle processor/Photo credit: IBM Quantum computers have the potential to speed up computation, help design new medicines, break codes, and discover exotic new materials—but that’s only when they are truly functional. One key thing that gets in the way: noise or the errors that are produced during computations on a quantum machine–which in fact makes them less powerful than classical computers – until recently. Daniel Lidar, holder of the Viterbi Professorship in Engineering and Professor of Electrical & Computing Engineering at the USC Viterbi School of Engineering, has been iterating on quantum error correction, and in a new... The paper, “Demonstration of Algorithmic Quantum Speedup for an Abelian Hidden Subgroup Problem,” was published in APS flagship journal Physical Review X.

How 2025's Unconditional Speedup Shattered Computing Barriers A single experiment proved quantum computers aren't just faster—they're fundamentally superior at tasks classical machines will never solve efficiently. When Nvidia's stock plummeted 17% in January 2025 after DeepSeek-R1's release 1 , the market signaled what scientists already knew: computational supremacy was shifting. But the true earthquake came months later, as a team from the University of Southern California (USC) and Johns Hopkins demonstrated an unconditional exponential quantum scaling advantage—a first in computing history 2 9 . This milestone didn't just improve speeds; it revealed problems where quantum machines outpace classical ones by orders of magnitude growing exponentially with complexity. For cryptography, drug discovery, and AI, the implications are revolutionary.

Quantum computing harnesses phenomena that defy classical logic: What was previously expressed only on paper has now been demonstrated in action. The promise of quantum computing has been achieved in reality, as they beat classical computers exponentially and unconditionally1. For this, a team of researchers, led by Daniel Lidar, a professor of Electrical & Computing Engineering at the USC Viterbi School of Engineering, used clever error correction and the powerful 127-qubit processors of... For decades, classical computing has been the norm. However, in recent years, quantum computing has undergone significant development.

An emerging area of computer science, quantum computing utilizes the principles of quantum theory (which explains the nature and behavior of matter and energy at the atomic and subatomic levels) to dramatically increase computation... Using quantum physics, quantum computing aims to solve problems that are too complex for the classical computers that we use on a daily basis. In fact, quantum computing can solve certain complex simulation problems that would even take a traditional supercomputer hundreds of thousands of years.

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