One! ... No, Zero! ... No, Both!

Tim Rambo, `09

### PhD Candidate

### Electrical Engineering and Computer Science

### McCormick School of Engineering, Northwestern University

Traditionally, bits are constrained to have a single value, either 0 or 1. Interestingly, if bits are treated as quantum mechanical objects, they are allowed to be a combination of both 0 and 1. Using this and other effects of quantum mechanics, it is possible to perform certain tasks better than the best known methods which rely on traditional (classical) bits. One example is the quantum algorithm for factoring large numbers, which is exponentially faster than the best known classical technique. Another example is that quantum bits can be used to distribute unconditionally secure cryptographic keys to geographically separated parties. Unfortunately, there are limited known useful computational applications for quantum computing, possibly because the language for describing quantum computation is complex and opaque to our classically-trained minds. In light of this, much work has gone into finding more intuitive models for quantum computers. In this talk, I will present the
mathematical description of quantum bits and operations. I will also discuss in detail two example uses of quantum information: quantum key distribution and quantum search. Finally, I will conclude by showing a new (hopefully) more intuitive model for quantum computation and our work in designing a proof of principle device to demonstrate the feasibility of this model.