IBM researchers have finally shown in a real-world experiment that quantum computers are superior to classical devices, though for now, only on a miniature scale.
The Big Blue quantum team set out to discover whether current quantum devices, despite their limitations, could be used to complete a task that cannot be accomplished in a classical system.
Since quantum computing is still in its infancy, the researchers leveled the playing field between the two methods by designing a microscopic experiment with limited space, that is, a limited amount of available memory.
Two space-limited circuits were built, one quantum and one classical, with only one bit or qubit available for computation and storage of results. The programmed task in the circuits was to find the majority of three input bits, returning zero if more than half the bits are zero and one if more than half the bits are one.
The restrictions, the scientists said, allowed for a fair comparison between the power of classical and quantum space when performing a calculation.
“Through our research, we are exploring a very simple question,” IBM’s quantum team said in a blog post. “How does computational power differ when a computer has access to classical scratch space versus quantum scratch space?”
Equipped with a single bit for computation and storage, the classical system is not capable of executing the algorithm, the scientists theorized. Even when the system’s computational capabilities were given a boost by adding what are known as random Boolean gates, the classical computer only succeeded 87.5% of the time.
Quantum devices, on the other hand, fared better: A perfect, silent quantum computer could succeed 100% of the time, the scientists said in their theory demonstration.
This is because, unlike classic bits that can represent a 1 or a 0, qubits can take on a combination of several states at once, which means they have access to a larger space of values. In other words, quantum space is more valuable than classical space.
The theory, however, is still some distance from reality. Current quantum computers are still too noisy to achieve the perfect results demonstrated by the scientists in their paper. But running the experiment in real life, with circuitry calibrated to run the program more efficiently, the IBM team still saw a 93% success rate, which beats the classical system.
“We show that qubits, even today’s noisy qubits, offer more value than bits as a storage medium during computations,” the scientists said.
This means that even today’s noisy quantum computers can deliver better performance on the problem than the theoretical maximum performance of a classical device, suggesting that as technology evolves, the performance gap with classical devices will only will expand.
The Big Blue quantum team claims this is the world’s first demonstration of quantum advantage, because the theory is backed by a real-life experiment.
To date, research projects are concerned with proving a theoretical quantum advantage that can only be demonstrated when the hardware is mature enough to run large-scale programs, according to the scientists.
From improve auto manufacturing supply chains for optimize merchant ship routes around the world’s oceans: There is no shortage of ideas when it comes to investigating how quantum computing could create business value. But for now, scientists are mostly finding that quantum technologies are comparable to classical systems for small-scale problems, only theorizing that quantum devices will eventually provide an advantage as computers develop.
“Here, for the first time to our knowledge, we report a simultaneous proof and experimental verification of a new type of quantum advantage,” the IBM researchers said.
As quantum hardware improves, it is expected that these experimental verifications will expand from tests performed at the level of individual bits. IBM recently unveiled a quantum roadmap for the coming yearswhich includes a 1,121-qubit system to be built by 2023, on track to create systems supporting more than a million qubits in the long term.