Group of students at the Max Planck Centre for Extreme and Quantum Photonics at the University of Ottawa. Credit: University of Ottawa

Imagine being stuck inside a maze and wanting to find your way out. How would you proceed? The answer is trial and error. This is how traditional computers with classical algorithms operate to find the solution to a complex problem. Now consider this: What if, by magic, you were able to clone yourself into multiple versions so that you were able to go through all the various paths at the same time? You'd find the exit almost instantly.

Turns out we're not talking about magic—we're talking atomic and subatomic particles. An electron, for instance, can be in multiple places at once. This is a fundamental principle of nature known in quantum mechanics as the superposition principle.

Now, imagine if we take advantage of this principle and apply it to our classical simulators and computers. Imagine how dramatically more efficient we'd be at information processing!

This is the principle behind quantum computers and quantum simulators. In essence, quantum computers use the subatomic particles' ability to exist in more than one place at once.

Quantum simulators are not just good for efficiency in processing times, but they are the "natural" choice to simulate simple and complex systems in nature. This is a direct consequence of the fact that nature is ultimately governed by the laws of quantum mechanics.

Quantum simulators provide us with an excellent opportunity to simulate fundamental aspects of nature and understand their hidden dynamics without even looking into the complexities arising from the various particles and their interactions. This is precisely the motive behind the research of Professor Ebrahim Karimi and his team.

Karimi's team simulates periodic and closed structures in nature, such as ring-shaped molecules and crystalline lattices, by invoking the quantum mechanical properties of light. The results can help us understand the dynamics involved in such systems as well as open the possibility for developing efficient photonic-based quantum computers.

Karimi's team has successfully built and operated the first-ever quantum simulator designed specifically for simulating cyclic (ringed-shaped) systems. A quantum simulator simulates a quantum system. The team used the quantum of light (photon) to simulate the quantum motion of electrons inside rings made of different number of atoms. The experiment results revealed that the physics of ring-shaped systems are fundamentally different from those of line-shaped ones.

In doing so, the team established a powerful experimental technique to simulate a wide class of atomic systems and opened a new window to explore many opportunities resulting from its work.

"We anticipate that, within a short period of time, our research will have a very large impact in various disciplines, ranging from medicine to computer science, from organic chemistry and biology to materials science and fundamental physics," says Dr. Farshad Nejadsattari, one of Karimi's postdoctoral fellows, who was part of the project.

In a quantum simulator, a quantum particle that can be easily controlled and is physically well understood (in our case a particle of light, a photon) is allowed to propagate inside a system designed to be similar to that which is being simulated.

Some interesting discoveries from this experiment includes finding specific ways to distribute the particle on the ring such that the distribution never changes as the particle propagates, and also finding cases whereby the particle first spreads itself on the ring and then re-emerges at the location where it was initially placed. This has never been seen experimentally in any quantum simulator.

With quantum simulation techniques becoming more mature and complex, synthesizing new materials, chemicals and drug development will be greatly simplified. The quantum simulator will help provide all the information one needs in the blink of an eye.

Explore further How does a quantum particle see the world?

More information: Farshad Nejadsattari et al. Experimental realization of wave-packet dynamics in cyclic quantum walks, Optica (2019). Journal information: Optica Farshad Nejadsattari et al. Experimental realization of wave-packet dynamics in cyclic quantum walks,(2019). DOI: 10.1364/OPTICA.6.000174