Researchers at the National Physical Laboratory (NPL) have achieved a notable breakthrough. They have, for the first time, imaged individual defects in superconducting quantum circuits! Two-Level System (TLS) defects are the Achilles heel for superconducting circuit-based quantum processors. Yet they are the principal perpetrators of decoherence in such systems. This revolutionary innovation can result in the development of powerful, robust and consistent quantum computers. These new machines may even surpass the power of any classical computer.
The research was done in partnership with Chalmers University of Technology and Royal Holloway University of London. For more than 50 years, scientists have studied the detrimental effects of TLS defects on QC. These disruptions lead to the erasure of important quantum information. Until recently, the capability to detect and investigate specific defects in a functioning quantum circuit had proved just out of reach.
Understanding TLS Defects and Decoherence
TLS defects TLS, or time-limited superconducting defects, are tiny flaws in superconducting circuits capable of wreaking havoc on devices. This process results in a loss of quantum behavior known as decoherence. Catastrophic error occurs when the quantum information encoded in a quantum computer escapes and is irretrievably lost. This process is especially harmful to the field of quantum computing, as it breaks the integrity of previously established calculations and data processing.
Dr Riju Banerjee, a senior scientist at NPL, who was one of the lead authors of the research paper stated just how significant this discovery is.
“For years people have believed that TLS defects perturb quantum circuits. It is remarkable to finally be able to visualize the fluctuations and decoherence each TLS defect causes as it interacts with the circuit.” – Dr. Riju Banerjee
Prior to this breakthrough, researchers were unable to study individual TLS defects and their precise contributions to decoherence in real-time. The difficulty in imaging these defects hampered progress towards developing scalable, stable quantum processors.
The New Imaging Tool
New research here at NPL has resulted in the development of a cutting edge tool. This unique tool combines state-of-the-art microscopy techniques with live quantum circuits. This instrument operates inside an extremely dark room, which is light-tight. The chamber is cooled to just above absolute zero, which reduces any thermal fluctuations that would make readings difficult.
Dr. Sebastian de Graaf, principal scientist at NPL, is enthusiastic about this new tool. For one, he thinks data like this will massively level the playing field for future researchers.
“We now have a new tool with which we can learn so much more about these nasty defects that plague quantum circuits. It can now help us to find ways to get rid of these [defects] in the future.” – Dr. Sebastian de Graaf
This new tool will now allow scientists to study the interaction of each TLS defect with its surrounding circuit. This accomplishment greatly improves our knowledge of what part these defects make in decoherence. All this wisdom will be indispensable for formulating plans to lessen or eradicate these flaws.
Implications for Quantum Computing
With the introduction of new imaging and analysis capabilities for TLS defects, researchers have taken a major step forward in quantum computing research. This breakthrough gives researchers the tools to develop more accurate and robust quantum computers. It’s only with these new systems that we will see them truly competing with classical computers. The study was published in the journal Science Advances. This research adds to the growing emphasis on developing better quantum technologies.
Transportation researchers are working furiously to better understand the ramifications of their findings. This applied research is helping to pave the way toward realizing functional and efficient quantum computers. The ongoing collaboration between NPL, Chalmers University of Technology, and Royal Holloway University of London signifies a commitment to overcoming existing challenges in superconducting quantum circuits.