For the first time ever, research scientists at the Massachusetts Institute of Technology (MIT) with the Institute for Soldier Technologies have demonstrated a level of control over the phenomenon known as quantum randomness.
If perfected, controlling quantum randomness could lead to a number of scientific breakthroughs, including the ability to perform previously impossible probabilistic quantum computing and advanced field sensing technologies.
Are Vacuum Fluctuations in the Quantum World Uncontrollable?
To achieve the breakthrough, the research team zeroed in on the phenomenon of vacuum fluctuations. A vacuum is typically depicted as an area of space completely devoid of any matter or energy. However, in the quantum realm, even the emptiest of space experiences minor fluctuations.
“Imagine a calm sea that suddenly gets waves,” the researchers explained in a press release announcing their breakthrough accomplishment, “that’s similar to what happens in a vacuum at the quantum level.”
Unlike the mathematically predictable movement of macro-scale objects that are governed by Newton’s laws of motion, motion in the quantum realm is effectively random. Such random fluctuations have allowed engineers to build random number generators that are truly random, a necessary tool in a number of areas of research, but have otherwise stymied many areas of research. That’s because, when scientists try to simulate the real world, the ability to factor randomness into the equation has been particularly elusive.
“Conventionally, computers function in a deterministic manner, executing step-by-step instructions that follow a set of predefined rules and algorithms,” explain MIT postdoctoral associates Charles Roques-Carmes and Yannick Salamin and MIT professors Marin Soljačić and John Joannopoulos in their published research. “In this paradigm, if you run the same operation multiple times, you always get the exact same outcome.”
This approach, they note, has powered the modern digital age from PCs to mobile phones, “but it has its limitations, especially when it comes to simulating the physical world or optimizing complex systems, tasks that often involve vast amounts of uncertainty and randomness.”
Researchers across a great number of fields, from virology and earthquake predictions to space exploration and even computer animation, have been searching for a method to add that randomness into their calculations. It is called probabilistic computing. And unlike conventional computers, probabilistic computing systems can offer a whole new way of simulating reality.
“They don’t just provide a single “right” answer, but rather a range of possible outcomes, each with its associated probability,” the researchers explain. “This inherently makes them well-suited to simulate physical phenomena and tackle optimization problems where multiple solutions could exist and where exploration of various possibilities can lead to a better solution.”
Unfortunately, no one has been able to effectively control the probability distributions associated with quantum randomness, at least not enough to make them usable in probabilistic computing scenarios. Now, the MIT team says, they have broken through that seemingly impenetrable wall by exerting just enough control over those random fluctuations to incorporate them into designs for a real-world probabilistic computer.
Quantum Randomness Controlled Via a Weak Laser Bias Injection
“Injecting a weak laser “bias” into an optical parametric oscillator, an optical system that naturally generates random numbers, can serve as a controllable source of “biased” quantum randomness,” they claim.
In effect, the MIT research team says they have tapped into previously unexplored territory and stumbled upon the ability to actually control random events, at least enough to make use of them in computer simulations.
“Despite extensive study of these quantum systems, the influence of a very weak bias field was unexplored,” said Charles Roques-Carmes, one of the researchers in the study. “Our discovery of controllable quantum randomness not only allows us to revisit decades-old concepts in quantum optics but also opens up potential in probabilistic computing and ultra-precise field sensing.”
As the press release explains, “The team has successfully exhibited the ability to manipulate the probabilities associated with the output states of an optical parametric oscillator, thereby creating the first-ever controllable photonic probabilistic bit (p-bit).”
Controlling Quantum Randomness May Usher in a Revolution in Probabilistic Computing
This new ability could theoretically lead to a revolution in probabilistic computing, and according to one of the researchers involved, they have already begun developing the designs to use this approach in actual computing systems.
“Our photonic p-bit generation system currently allows for the production of 10,000 bits per second, each of which can follow an arbitrary binomial distribution,” said researcher Yannick Salamin. “We expect that this technology will evolve in the next few years, leading to higher-rate photonic p-bits and a broader range of applications.”
The possible applications and seemingly unlimited potential of such a system were also highlighted by team member and MIT Professor Marin Soljačić.
“By making the vacuum fluctuations a controllable element, we are pushing the boundaries of what’s possible in quantum-enhanced probabilistic computing,” Soljačić said. “The prospect of simulating complex dynamics in areas such as combinatorial optimization and lattice quantum chromodynamics simulations is very exciting.”
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.