Events

No, you have not discovered a Majorana Fermion

Abstract: Is what I tell myself. There was a time when I thought I may have discovered it, others did too. Around 2012 several groups including ours found evidence of these quantum excitations in electrical circuits containing nanowires of semiconductor covered by a superconductor. The dramatic signatures were peaks in conductance that appeared under conditions expected from theory for Majorana modes, which are their own anti-modes and may possess non-Abelian properties. But a few years later, similar features in the data were identified due to an interesting, but a more mundane effect - which we call trivial states such as Andreev bound states. Over time more and more data pointed at the trivial and not at the exotic explanation. But because Majorana claims kept coming, this led to some digging and even retractions. What we learned after 10 years is that we have a much better handle on what effects show up in these nanowires, which positions us well for the ultimate Majorana discovery which we should be able to tell apart from all the non-Majorana things we saw. The second lesson we learned is that materials quality of device constituents, superconductors and semiconductors, as well as how samples are fabricated - are the make-or-break factors for making this happen. So while  I cannot report an exciting physics discovery, I can walk you through the scientific process that took place, a 10-year event of independent value which taught me how to do science better.

Join us for Quantum Today, where we sit down with researchers from the University of Waterloo’s Institute for Quantum Computing (IQC) to talk about their work, its impact and where their research may lead.

IQC CS/Math seminar - Marc-Olivier Renou (INRIA, Paris-Saclay)

Quantum correlations are obtained when multiple parties perform independent measurements on a shared quantum state.  Bell’s seminal theorem proves that certain correlations predicted by quantum theory resist explanations in terms of any Local Hidden Variable theory based on shared randomness. But what about alternative explanations for quantum correlations, in terms of a hypothetical causal theory involving exotic bipartite resources generalising quantum bipartite entanglement in addition to shared randomness? 

IQC Special Seminar Featuring Gerardo Adesso, The University of Nottingham

What makes quantum technologies tick? Advantages in communication, computation, metrology and other applications can be traced back to distinct manifestations of quantum theory, such as coherence and entaglement.

IQC Colloquium - Dvira Segal, University of Toronto

Rethinking the operation principles of thermal machines in the nanoscale and quantum domain, we focus on a continuous machine operating in steady state, the quantum absorption refrigerator (QAR), and examine three key questions: (i) How does the strong system-bath interaction affect the device's operation? (ii) What can we learn about the machine from current noise? (iii) What is the impact of coherences within the working fluid on the performance of the quantum machine? 

13-level Qudit Measurement Demonstrated in Trapped Ions

CS/Math seminar - Igor Klep, University of Ljubljana

The talk will discuss state polynomials, i.e., polynomials in noncommuting variables and formal states of their products. The motivation behind this theory arises from the study of correlations in quantum networks. We will give a state analog of Artin's solution to Hilbert's 17th problem showing that state polynomials, positive over all matrices and matricial states, are sums of squares with denominators.

Graphical CSS Code Transformation Using ZX Calculus

Math/CS Seminar - Featuring Olivier Lalonde Université de Montréal

Quantum communication complexity, which concerns itself with determining how much communication is required by two participants having access to quantum resources to compute a boolean function of their inputs, has long been a lively subfield of quantum information science. The topic of this talk will be the power of shared prior entanglement relative to quantum communication without prior entanglement, which, despite having been studied for more twenty years, remains rather mysterious. After a quick review of the bare bones of classical communication complexity, I will proceed to discuss the model of entanglement-assisted communication complexity.