During the 20th century, many scientists, including Nobel laureates, wondered about the nature of superconductivity, which was discovered by Dutch physicist Kamerlingh Onnes in 1911. In superconductors, a current flows through a wire without no resistance, which means inhibiting this current or even blocking it is hardly possible – much less passing current in one direction and not the other. That Dr. Heng Wu and Dr. Yaojia Wang, the principal researchers in Ali’s group who conducted this study, succeeded in making unidirectional superconductivity – necessary for computing – is remarkable: it can be compared to the invention of a special type of ice that gives you zero friction when skating one way, but insurmountable friction the other way.
Q: Why, when unidirectional direction works with normal semiconductor, has unidirectional superconductivity never worked before?
A: Mazhar Ali: “Electrical conduction in semiconductors, such as Si, can be one-way due to a fixed internal electric dipole, hence net built-in potential they may have. The classic example is the famous” pn junction”; where we assemble two semiconductors: one has extra electrons (-) and the other has extra holes (+). Charge separation creates a net integrated potential that an electron flowing through the system will feel. This breaks the symmetry and can result in “one way” properties. because forward vs backward, for example, is no longer the same. There is a difference between going in the same direction as the dipole or go against it; it’s like swimming with the river or going up the river. Superconductors have never had an analogue of this one-way idea without a magnetic field; since they are more related to metals (that is, i.e. to conductors, as their name suggests) than to semiconductors s, which always conduct in both directions and have no built-in potential. Similarly, Josephson Junctions (JJ), which are sandwiches of two superconductors with conventional non-superconducting barrier materials between the superconductors, also did not have a particular symmetry breaking mechanism that resulted in a difference between “before ” and “rear”.
Q: How did you manage to do what initially seemed impossible?
Q: What does this discovery mean in terms of impact and applications?
A: “Many technologies are based on older versions of JJ superconductors, for example MRI technology. Moreover, quantum computing today is based on Josephson Junctions. A technology that was previously only possible using semiconductors can now potentially be made with superconductors using this building block.This includes faster computers, as in computers with up to terahertz speed, which is 300 to 400 times faster than the computers we are currently using. This will influence all sorts of societal and technological applications. If the 20th century was the century of the semiconductor, the 21st may become the century of the superconductor. The first direction of research we need to address for commercial application is the operating temperature rise. Here we used a very simple superconductor that limited the temperature. operating failure. Now we want to work with so-called “High Tc Superconductors”, and see if we can run Josephson diodes at temperatures above 77 K, as this will allow for liquid nitrogen cooling. The second thing to tackle is scaling up production. While it’s great that we’ve proven it works in nanodevices, we’ve only made a handful. The next step will be to investigate how to expand production to millions of Josephson diodes on a chip.”
Q: How sure are you of your case?
A: “There are several steps that all scientists must follow to maintain scientific rigor. The first is to ensure that their results are reproducible. In this case, we have manufactured many devices, from scratch, with different batches of materials, and found the same properties every time, even when measured on different machines in different countries by different people. This told us that the Josephson diode result came from our combination of materials and not from a false result of dirt, geometry, machine or user error or interpretation.We have also performed “smoky” experiments which greatly reduce the possibility of interpretation.In this case, to be sure that we had a superconducting diode effect, we actually tried to “switch” the diode; as in we applied the same magnitude of current in both the forward and In the opposite way. opposite direction and showed that we had measured no resistance (superconductivity) in one direction and real resistance (normal conductivity) in the other direction. o measured this effect when applying magnetic fields of different amplitudes and showed that the effect was clearly present at 0 applied field and was killed by an applied field. It is also an irrefutable proof of our claim to have a superconducting diode effect at zero applied field, a very important point for technological applications. This is because nanoscale magnetic fields are very difficult to control and limit, so for practical applications it is generally desired to operate without requiring local magnetic fields.”
Q: Is it realistic for ordinary computers (or even supercomputers from KNMI and IBM) to use superconductivity?
Source and top image: TU Delft