What do quantum computers and the computer game Guitar Hero have in common? At the Qubit building on the TU/e campus, they have been combined to create the first ever quantum computer game known as Qubit Hero. The game was created to mark the recent launch of a state-of-the-art quantum computer simulation or digital twin which is part of the Quantum Inspire platform. The new digital twin of a quantum computer is accessible online, meaning that anyone with a little understanding of quantum computers can write simple computer codes and run them on the digital twin.
Unlike in classical computers where information is stored in bits as 0 or 1, information in quantum computers is stored in qubits, which can store 0 and 1 at the same time, otherwise known in quantum physics as superposition.
Researchers at TU/e - led by Servaas Kokkelmans who is group leader of the Coherence and Quantum Technology group - are currently busy building two neutral atom quantum computers .
However, before the physical quantum computers go live, Kokkelmans and his team at TU/e have opted to launch a digital twin of a quantum computer first.
Why a digital twin?
Kokkelmans' long-term goal is to have the physical quantum computers online so that anyone from the public with the right training can program the quantum computers.
While Kokkelmans and his team work on getting the computers ready to go live, he wanted to give future users a taste of what it would be like to use a quantum computer.
"Thanks to the digital twin, users can already get accustomed to what is possible and not possible with current neutral atom quantum computers," says Kokkelmans. "And we can use the digital twin to simulate some of the physics of our real quantum computers that will guide the hardware development. The new insights will prove invaluable."
Connection to the Quantum Inspire network
Earlier this summer, quantum enthusiasts at the TU/e campus and from the quantum community in the Netherlands gathered to mark the official launch of the digital twin quantum computer, which is now connected to the Quantum Inspire platform .
In addition, they got the chance to visit the neutral atom quantum computers ( Ruby and Sapphire) in the basement of the Qubit building. In these computers, atoms are held in place with a laser in an ultra-high vacuum, and each atom represents one qubit.
Who wants to be a Qubit Hero?
Perhaps the highlight of the day was the Qubit Hero game - where the popular computer game Guitar Hero was adapted with a quantum computing twist. In the original game, players use a guitar-shaped controller to match color-coded notes on-screen with the corresponding buttons on their controller, simulating the act of playing a song. Kokkelmans elaborates on how the quantum version of the game works.
"To play Qubit Hero you first select a song, and the quantum gates drop down on the rhythm of the song (which in the original game would be the notes a player needs to hit at the right time). Information about whether you press the right button or not is monitored. Errors are collated to represent an error signal which is sent in real time to the quantum computer Ruby."
"Each mistake results in an additional small error on the laser pulse that controls a quantum gate operation, that in turn results in less qubits reaching the right state, an outcome which is visible in the game. The number of visible qubits therefore keeps dropping when you are making more mistakes. The fidelity (which is a measure of the accuracy and reliability of the qubits) is calculated at the end and this is your score on the leader board."
So, in short, the aim of Qubit Hero is to keep the quantum computer operating on as many qubits as possible, keeping the errors to a minimum. Players get a feel for how difficult it is to keep a quantum computer in a stable state.
(Photo: Odette Beekmans from Photodette)
Supercomputer assistance
Putting the importance to 'rock out' to one side, let's get back to how the digital twin simulates a quantum computer.
There is a slight conundrum to solve problems using a digital twin quantum computer. Given that it simulates a quantum computer and it's not a physical computer, where are the algorithms solved?
"We simulate the neutral-atom quantum computer using a very powerful supercomputer on the High Tech Campus in Eindhoven," says Kokkelmans.
In theory, the digital twin can be used to solve a problem with 50 qubits, but this only works for algorithms that are not very complex and relatively easy to solve right now.
"For more complicated algorithms, we simulate with a lot less than 50 qubits. Now, the digital twin is set to run with 9 qubits, but in a few weeks, we are aiming to increase this number. We hope to reach 25 qubits very soon, which means that we can run more complex algorithms and solve them on the supercomputer."
Target users? Everyone!
The Quantum Inspire platform to which the digital twin is connected is open to the entire world to use, which means that anyone can use it. But, who are the target users for the quantum computer digital twin according to Kokkelmans?
"In theory everyone can use it, but we are targeting those who want to explore new types of algorithms that work well with neutral atom quantum computers at TU/e . Of course, it can also be used in courses for the teaching of quantum computing. I will be using it in my course, and I'll encourage my colleagues to also do so."
Important milestone
The launch of this digital twin of the forthcoming quantum computer at TU/e is significant for the university and the quantum technology ecosystem Quantum Delta NL (QDNL), as outlined by the Director of Research Programmes and IP Pieter de Witte.
"This is an important milestone in our QDNL programme, and it represents the 3rd qubit technology on the national quantum computer Quantum Inspire," says de Witte. "The open character of Quantum Inspire will allow all kinds of users to experience what it's like to use a neutral atom, laser-controlled quantum computer. It'll allow us to collect valuable feedback for future technology development."
What's next for quantum at TU/e?
Next up for quantum computing at TU/e is the formal online launch of the physical quantum computers at the Qubit building on campus, which is planned for some time in 2026.
"For this, we are working on improving the reliability of the laser transitions when it comes to stimulating the excited atomic Rydberg states in the computers. The fidelity is not yet high enough, and it also only works on a limited number of qubits," says Kokkelmans. "There is still a bit of work to do before the computers go online, but we are getting there. Watch this space!"
