Scientists at Los Alamos National Laboratory have made an exciting breakthrough in quantum computing: they’ve identified a new problem that only a quantum computer—not a traditional one—can solve efficiently.
This adds to a very short list of known problems where quantum computers have a clear advantage, something researchers consider the “Holy Grail” of the field.
For years, quantum computing has held the promise of revolutionizing how we solve problems in areas like cryptography, physics, and data science.
But in reality, scientists have only found a few problems that quantum computers can solve better than classical ones.
Now, in a new paper published in Physical Review Letters, the Los Alamos team has officially added one more to that list.
The problem they studied involves simulating a highly complex optical circuit—a kind of system made up of light beams, partially reflective mirrors (called beam splitters), and phase shifters.
These systems, called Gaussian bosonic circuits, can behave in ways that are extremely hard to model using regular computers.
In fact, trying to write down every detail of this system would take an overwhelming amount of memory and computing power.
But quantum computers, which work using the strange rules of quantum physics like superposition and entanglement, can handle such complexity far more easily. The Los Alamos team was able to use a quantum computer to simulate this intricate optical setup in a practical amount of time.
What makes this discovery so important is that the researchers didn’t just do the simulation—they proved that it belongs to a class of problems called “BQP-complete.”
This category includes problems that are believed to be nearly impossible for classical computers to solve, but relatively easy for quantum computers. In other words, if you can solve one BQP-complete problem with a quantum computer, you can solve all of them.
This insight builds on earlier research suggesting that quantum computers could simulate networks of masses and springs. The Los Alamos team took that idea a step further by switching from classical systems to quantum ones—specifically, using light in optical circuits.
The breakthrough came with the help of Alice Barthe, a student from the Quantum Computing Summer School at Los Alamos who also works with CERN in Switzerland. Her background in both quantum algorithms and optical systems helped the team overcome a major challenge in their research.
Lead scientist Marco Cerezo emphasized how crucial her contribution was, saying this success shows not only the power of quantum computing, but also the value of strong collaboration and fresh talent.
This discovery marks a big step forward in quantum research—and gives us one more reason to believe in the future of quantum computing.
