To understand quantum computing, we spoke to Erik Lucero, PhD, researcher and site manager for Google Santa Barbara, the company’s Quantum AI campus. Lucero ’05 began his studies at CU Denver, where he earned a double major in Electrical Engineering and Physics.
Bits, Qubits and Overlay
Before we move on to quantum computing, let’s demystify a few terms. Quantum simply means very small. Quantum mechanics is mankind’s best theory explaining the behavior of nature. Combine the quantum with computers, and you have a computer that calculates with quantum mechanics.
“We are building a new kind of computer,” Lucero explained. “It’s important to understand what we have for computers today. We call these classic computers. A classic computer is like an abacus; its calculation is governed by Boolean logic. The fundamental building blocks on a classical computer are called bits, which can be 0 or 1. In quantum computing, building blocks are called qubits (short for quantum bits). Qubits can exist on a spectrum. “We describe it as an overlay, that is, the qubit can be both zero and one. And with this richer set of computational space, a quantum computer replaces Boolean logic with the laws of quantum mechanics. In short, a quantum computer can explore a richer computing space than a classical computer. It’s not either, it’s both. How much is in 0? How much is it in 1? Lucero said.
What does it do?
The complex superposition of qubits mimics the behavior of molecules in the real world. But what can quantum computers actually do? “We believe quantum computers could be useful for specialized applications that a quantum computer can do faster than a conventional computer,” Lucero said. For example, quantum computing could be used to create more efficient batteries that are not dependent on rare earth metals.
Or it could positively affect the way we feed the world. “One to two percent of all human energy consumption goes to the production of fertilizers,” Lucero explained. “With an error-corrected quantum computer, we believe we can model the chemical process used by nature to fix nitrogen and turn it into fertilizer with much lower energy consumption.” The ultra-fast quantum computer could also be used to invent and test new medical therapies. By modeling the behavior of molecules in a given scenario, scientists could save time and resources by avoiding making targeted drugs that won’t work. “These types of therapy are a big investment,” Lucero said. “If you could do the mock testing first, you could make the drug discovery process cheaper.”
But first, Lucero and his team at Google need to upgrade their existing quantum computer to become an error-correcting quantum computer. In other words, he must correct the errors he makes as he makes his calculations. “We have published a roadmap,” Lucero said. “Over the next 10 years, we believe we can build an error corrected quantum computer. “
Right now, Google’s quantum computers are starting to show how to fix mistakes (Nature, July 14, 2021). And they showed that for specific problems, they can perform calculations on their quantum computer in a few hundred seconds, which would take 10,000 years for a supercomputer (Nature, October 23, 2019). They perform calculations at very fast speeds, exponentially faster than conventional computers. Part of this is achieved through specialized refrigeration. Quantum computers require cryostats (super refrigerators) to ensure the proper functioning of superconducting qubits. “The water freezes at 273 Kelvin,” Lucero explained. “Our refrigerator goes down to 10 millikelvins, which is cooler than intergalactic space.”
Photography captures technological progress
One of Lucero’s passions is photography, and he believes it has similarities to quantum computing. In a recent episode of The Artian podcast, Lucero said that both disciplines require “special order and exquisite care”.
Lucero’s photographs have also served as historical testimony to advances in quantum computing processors. “I have a cool lineage of all the processors I’ve worked on,” he said. “I share this with other team members to encourage others to document so that I can talk about their work by showing and explaining.”
His photographs help people see what quantum computers really look like. “Pictures really bring things to life,” he said. For visual learners, this is very useful. But Lucero has also gotten pretty good at describing Google’s quantum processor. “It looks like a chandelier,” he said. “A large metal stage with a number of layers of beautiful threads.”
Beyond classical calculations
Google’s goal is to build an error-correcting quantum computer. To do this, Lucero and his team will rely on established science. “We stand on the shoulders of giants,” he said. He credits the “Nobel Prizes in addition to the Nobel Prizes” for having laid the foundations for the golden age of quantum material.
He also credits CU Denver for some of his own success. “I want to recognize Martin Huber, a great advisor, mentor and friend. Martin does impressive research with undergraduates, world-class research comparable to any research university. Lucero also credits Associate Professor Randy Tagg for his “great ability to teach intuition and generate enthusiasm among engineers for physics.”
Lucero, who is a first generation student, learned about the possibility of becoming a career seeker at CU Denver. “I had no idea of the trajectory of higher education,” he admitted. “The combination of opportunities I had at CU Denver, the talented teachers I had direct access to, the small classes and the incredible mentorship from Martin [Huber], allowed me to make higher education my goal.
Over the next decade, Lucero will have a new goal besides building an error-correcting quantum computer: building his quantum computing team. “As a leader in this field, I am thinking of the next wave of talent,” he said.