You probably heard of quantum computers and their incredible abilities to solve complex operations in no time. There are actually multiple layers needed for a quantum computer to operate this way, from the hardware quantum layer to the classical control electronics layer.
The real quantum computing challenge for so long was to perform quantum operations with less than 1% error percentage. This is the 99% fidelity of quantum operations that researchers were going for with all of their resources and time. Until today when UNSW University physicists finally made it true.
This blog will discuss UNSW’s breakthrough, but first, let us rewind and explain quantum computing chips and error-free quantum operations from scratch.
What Is a Quantum Chip?
Just like classic computer chips, a quantum chip is a small integrated circuit made of semiconductor material that comprises the operation and memory of qubits. The latest quantum chips can hold and operate up to 127 qubits all in sync, thus increasing the memory space needed for advanced algorithms.
The 127 qubits synchronization isn’t the most exciting part yet. The real research quantum leap is setting a blueprint for fabricating quantum chips using the same manufacturing plants that make today’s silicone chips.
Diving into a smaller scale, we will explain…
What Are Qubits?
Qubits or quantum bits are the smallest units of quantum information. Qubits can exist in 2 states at once. How? You’re probably more familiar with the digital binary system of 1 and 0 bits. Qubits are the counterpart of bits in a quantum system that can be a 1 and a 0 at the same exact time.
There are different types of qubits such as superconducting qubits, solid state qubits built by scientists, natural qubits made from things in the world around us, like atoms or ions. Quantum bits are not just atoms or ions though, they result in totally different and advanced properties.
Among qubits properties is fidelity. Qubit fidelity is a measure of a qubit’s ability to perform practical, efficient, and error-free operations. This is the key feature in the quest to develop quantum computers that we discussed earlier.
Researchers at UNSW, The University of New South Wales, Sydney, led the quest, being the first to achieve a two-qubit silicon quantum device operating at an unprecedented level of fidelity. At 99.8%, this is the highest fidelity achieved so far for a two-qubit gate in a semiconductor qubit type.
Researchers used a silicon device called a double quantum dot to capture two electrons and force them to interact. Electrons have a spin, which is their angular momentum. It’s a quantum property that manifests the magnetic dipole responsible for encoding information. You can compare the electron’s spin to the magnet’s North and South poles that cause the magnet’s attraction or repulsion.
The spin state of each electron is also considered as a qubit that can exist in 2 states: spin up and spin down. Thus, the interaction between the electrons can superpose these qubits. This crucial superposition or entangling operation was performed at a fidelity level exceeding 99.8%. It’s a milestone for quantum computation.
If you thought the 99.8% is in itself the breakthrough, allow us to dissect the many other advantages that this 99.8% fidelity chip has to offer.
99.8% Fidelity Advantages
When there’s only a 0.2% chance of error left, it’s relatively easier to detect and correct these errors. While error percentages reached above 10% in the best qubit chips, the 99.8% fidelity chip promises to build quantum computers with enough scale, power, and accuracy to handle meaningful computation.
Stability and Scalability
As mentioned above, the 99.8% fidelity chip is a semiconductor silicon type chip. Which means, this chip combines the highest fidelity with silicon’s finest properties. Semiconductor spin qubits in silicon are highly stable. The spin state, considered as the qubit, is extremely isolated from environmental disturbances.
Therefore, errors in qubits can be corrected faster and quantum information in these qubits can be held for longer periods. We’re talking 35 seconds long periods of information retention. That’s an eternity in quantum years. Silicon qubits also managed to overcome the scalability limitations in quantum chips.
The 99.8% fidelity chip is about 100 nanometers in size, compared to a conventional superconducting qubit of 300 microns in size. Thus, silicon chips can fit a larger number of qubits. So, you may add today to the long list of days that illustrate the benefits arising from free academic research.
Whether it’s in the field of quantum computing or not, ideas, knowledge, people, and material are meant to circulate freely and drive humanity forward.