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DWC Seminar Series 2017


 
The DWC is hosting a series of seminars and public lectures open for everyone to attend, details can be found below.  

 

what's on THIS week: 

The Dodd-Walls centre is proud to present a series of seminars hosted by our themes on different topics and everyone is welcome to attend.   Friday’s seminar is presented by Vladimir Bubanja from Measurement Standards Laboratory of New Zealand, Callaghan Innovation, Lower Hutt.  

Title:       Electron Transport in Hybrid Superconducting Devices

When:    Date: Friday 24 March, 12 noon (sharp) to 1.00pm

Room:   Dodd-Walls Centre Boardroom (University of Otago); 301.411, University of Auckland + remote locations via Zoom

Anyone can join from anywhere with the use of a laptop or computer via Zoom.

 Zoom Meeting ID: 478-489-695 

 Abstract:

Nanoscale tunnelling structures in low temperature environments provide the basis for the development of metrological sources of electric current. The new definition of the ampere, scheduled to be adopted in 2018, will be based on the exact numerical value of the elementary charge, e, and in practice will be realised by utilising sources that transfer electrons one by one. For this purpose we study the operation of hybrid turnstiles, consisting of a combination of superconducting and normal metal electrodes, and consider ways to improve their accuracy by suppressing the undesirable multi-electron tunnelling processes. In the case of a turnstile consisting of normal metal electrodes, separated by insulating layers from a superconducting island (NISIN), the main mechanisms that limit the accuracy of the device are elastic and inelastic cotunneling processes. On the other hand, in the case of a SINIS turnstile, the dominant errors are caused by the Andreev reflection and Cooper-pair-electron cotunneling processes. We show that by choosing the appropriate on-chip circuit impedance, these devices can be designed to satisfy the stringent metrological requirements on accuracy.

It is often the case in precision metrology that the pursuit of high accuracy leads to understanding of new physics. In the case of single electron sources, the understanding of the errors in the device operation led to advances in the description of non-equilibrium phenomena of quantum multi-electron processes. Interestingly, while these processes are detrimental to the operation of the single-electron devices in metrological applications, they perform the key function in information processing applications.