By introducing crystal resonance and magnetic fields, quantum engineers from UNSW Sydney made a critical breakthrough for quantum computers. They called it “the missing jigsaw piece” in quantum computer architecture.
Phys.org reports that the researchers had a “lightbulb moment” when UNSW’s Jarryd Pla reimagined the tiny silicon chip structure. Before their redesign, quantum computers delivered microwave magnetic fields through tiny complex wires on the chip.
With this structure, quantum processors could control no more than about 100 qubits, the smallest unit of information in quantum computing.
It’s not very efficient, and the heat produced by wires makes it challenging to keep the chips below -270°C, a requirement for functionality.
Nearby qubits, the building blocks of quantum computers, could be controlled in proximity to the wires. However, further away, the magnetic field was not strong enough to affect qubits at a distance. Taking quantum computing to the next level would require about a million qubits, not only a few. Thus, quantum engineers needed a eureka moment.
A Crystal Prism and Magnetic Control Fields
In the 1990s, an idea to control qubits all at once (global control ) was proposed using externally applied electric fields instead of wires. However, at the time, it would need “future refinements of conventional silicon electronics” to become real.
Two decades later, engineers have landed on how to deliver a magnetic field at a “suitably low power” with a dielectric resonator crystal. The small transparent crystal can briefly trap microwaves from the magnetic field (resonance).
“The trapping of microwaves, a phenomenon known as resonance, allows them to interact with the spin qubits longer and greatly reduces the power of microwaves needed to generate the control field. This was vital to operating the technology inside the refrigerator,” wrote the researchers.
By focusing microwaves through the crystal, the wavelength shrinks down to less than a millimeter. Then, the resulting oscillating magnetic field can control the spin of qubits. By controlling all the qubits at once, the team says it will improve reliability and reduce the rate of errors.
Since not much power is needed, there isn’t much heat generated. Then, the uniform field can simultaneously control millions of qubits.
Fascinatingly, qubits can be in two states at once, called the superposition state. Consequently, they can vastly outperform today’s classical bit, represented by either a 0 or 1.
Crystals and Magnetic Fields, New or Ancient Idea?
Talking about crystals and magnetic fields doesn’t sound like a new idea, does it? Rather, it sounds ancient. For example, many people have suggested ancient megalithic monuments found worldwide once functioned in unknown ways.
Crystals were part of ancient standing stones, astronomical observatories like Stonehenge, obelisks, and the lining of ancient pyramid passageways. Made of granite and moved over vast distances, these structures contained a high percentage of crystals.
Were ancient people using crystals as some means of focusing magnetic fields? Or, were they using quartz crystal because of its extreme durability, standing up to the elements after thousands of years? If so, would they have known that an “interlocking mosaic of quartz crystals” would stand the test of time?
It’s something to think about, seeing how crystals and magnetic fields are becoming part of potentially world-changing technology today.
The Future for Quantum Computing
Whether the idea is new or ancient, crystal resonance and magnetic fields could control millions of qubits, possibly leading to enormous leaps in computing. As a result, it could transform technology and society in unforeseen ways.
For now, more work is needed before scaling up to millions of qubits, but the engineers are confident it will happen.
“Major efforts are underway at UNSW Sydney to make quantum computers from the same material used in everyday computer chips: silicon. A conventional silicon chip is thumbnail-sized and packs in several billion bits, so the prospect of using this technology to build a quantum computer is compelling,” stated Jarryd Pla and Andrew Dzurak.
See Pla and Dzurak below from UNSW: