Study illustrates the necessity of shielding the qubits against natural radiation such as cosmic rays that come from space.
A multidisciplinary research team has demonstrated that the radiation of natural sources found in the world could hinder the performance of quantum bits, also known as qubits. The research, published this morning in Nature, is a major development regarding the operation and construction of quantum computer systems, an advanced type of technology that’s drawn billions of dollars of private and public investments across the globe.
Collaboration between teams from the U.S. Department of Energy’s Pacific Northwest National Laboratory (PNNL) and the Massachusetts Institute of Technology (MIT) could help uncover the interference source that limits qubit performance.
“Our own examine is the first ones to show evidently in which low-level ionizing light around the surroundings degrades the performance associated with superconducting qubits,” explained Steve Orrell, a new PNNL investigation physicist. He is a lead author on the study and an expert on low-level radiation measurements. “These findings declare that irradiation safeguarding will probably be required to attain long-sought functionality around massive computer systems of your design.”
Organic irradiation can cause havoc on computers.
Computer engineers have been aware for at least a decade now that natural radiation emitted by concrete or other materials and radiating through the atmosphere as cosmic rays could cause computer systems to fail. However, digital computers aren’t as robust as quantum computers.
“We all found that practical quantum computing having the product will not be done except in cases where most people tackle rays problem,” claimed PNNLphysical scientist Brent VanDevender, a co-investigator on the study.
Natural radiation can cause interference with Superconducting Dark Matter detectors (seen in this image) in addition to superconducting qubits. Photo credit: Timothy Holland, PNNL
The researchers came together to resolve a mystery that has made it difficult for a long time to make the superconducting quantum computer run for sufficient time to make them efficient and useful. A quantum computer that is working could have a speed that is thousands of times more efficient than the current top supercomputer. Furthermore, it could take on computer problems that modern digital computers aren’t able to handle. The first hurdle is to make qubits remain in their current state of being, which is known as “coherence,” said Orrell. The desirable quantum state is the basis of quantum computers’ capability.
MIT scientist Will Oliver was working with superconducting qubits when he became puzzled at the source of interference which helped push the qubits from their state of preparation, which led to “decoherence” and making qubits inoperable. After deciding on a range of possibilities and possibilities, he pondered the possibility that radiation from natural sources such as metals in soils and cosmic radiation from space could cause the qubits to enter incoherence.
A chance encounter with Oliver, VanDevender, and his long-time collaborator, MIT physicist Joe Formaggio, resulted in the current research.
It’s just natural
To test the concept that superconductivity is a good idea, the research team tested the performance of the prototype superconducting qubits in two tests:
- The qubits were exposed to the high radiation of copper, which was activated by reactors.
- They constructed a protective barrier around qubits, which decreased radiation levels that were in their environment.
The experiment showed clearly the relationship between the radiation levels and the amount of time that qubits are in an encapsulated state.
Natural radiation, such as X-rays, cosmic rays, beta rays, and gamma rays, can be absorbed by a superconducting qubit and disrupt quantum coherence. Source: Michael Perkins, PNNL
“The radiation splits the pair of electrons that normally carry electrical current with no resistance inside a superconductor.” claimed VanDevender. “The resistance of these unpaired electrons wrecks the smoothly geared up point out of a qubit.”
They concluded that the results are immediate and have implications for the design and development of quantum computers. In particular, the materials used to build quantum computers must be free of substances that emit radiation, according to the researchers. Additionally, it could be necessary to protect quantum computer systems from radiation from the air. At PNNL, there is a renewed interest towards whether they can use the Shallow Underground Laboratory, which reduces radiation exposure to the surface by 99%, which may aid future quantum computer research. A study conducted by a European research team supports the increase in the qubit’s coherence when tests take place underground.
A worker worked in the ultra-low radiation laboratory with the Short Below ground Science lab and Pacific ocean Northwest Countrywide Laboratory. Credit: Andrea Starr, PNNL
“Devoid of mitigation, radiation is going to restriction the coherence amount of superconducting qubits to a couple of milliseconds, which can be too little concerning useful massive computing,” reported VanDevender.
The researchers stress that variables that are not radiation exposure pose a greater threat to the stability of qubits for the time being. Things like microscopic imperfections or impurities in the material used to make qubits are the primary cause of the current limit on the performance of around one-tenth of milliseconds. Once those limits are overcome, radiation starts to establish itself as an issue and could eventually be a problem if there aren’t proper natural shielding strategies for radiation, according to the researchers said.
Findings influence global searches for dark matter.
Alongside helping to understand the source of qubit instability, the study results could also impact the global search for dark matter that is believed to be around 85 percent of the known universe yet has been largely obliterated by human detection by current instruments. One strategy to detect signals is using research-based superconducting detectors that are similar in structure to qubits. Dark matter detectors need to be protected from radiation coming from outside sources since radiation could cause false recordings, obscure the desired signal from dark matter.
“Enhancing the familiarity with this procedure can lead to increased patterns for these superconducting detectors plus lead to additional very sensitive dim make any difference researches,” mentioned Bill Loer, some PNNL researcher in physics. He works on dark matter detection and radioactivity effects in superconducting qubits. “All of us can also be able to use our knowledge of these kinds of compound science alarms to improve long-term superconducting qubit designs further.”
To get more information on this study, click here. Quantum Computing Performance May Soon hit the Wall due to interference from Cosmic Rays.
Source “Impact of ionizing radiation on superconducting qubit coherence” by Antti P. Vepsalainen Amir H. Karamlou, John L. Orrell, Akshunna S. Dogra, Mary Loer, Francisca Vasconcelos Jesse K. Betty, Alexander J. Melville, Bethany M. Niedzielski, Jonilyn L. Yoder, Simon Gustavsson, John A. Formaggio, Brent A. VanDevender and Bill D. Oliver, 26 Aug 2020, Nature.