Quantum Information Science and Technology

(QuIST)

Stewart D. Personick (sdp)sdp@ece.drexel.edu

Quantum Information Science and Technology

(QuIST)• This is a seminar course (informal,

interactive)• Attendance is mandatory

3 absences: no penalty>3 absences: -5 points per excess absence

• Grading: based on homework and participation

• No exams

Overview

• Preview• The concept of the “quantum state”

of a physical system or a collection of physical systems

• The concept of a quantum computer• The implications of the quantum

model on communications• Examples, in depth

Preview

• Mathematical models of the physical world:

Newton’s laws (e.g., F=ma)Maxwell’s equations Quantum theory

Preview

• Mathematical models of the physical world:

Newton’s laws (e.g., F=ma)• Observations

-Newton’s laws can be used to explain and model the behavior of physical systems-Not much is counter intuitive about what is predicted (exception: heavy objects fall no faster than light objects)

Preview

• Mathematical models of the physical world:

Maxwell’s equations• Observations

-Maxwell’s equations can be used to explain and model the behavior of physical systems-Much of what is predicted is, at least initially, not very intuitive… but it is not counter intuitive either

Preview

• Mathematical models of the physical world:

Quantum Theory• Observations

-Quantum theory can be used to explain and model the behavior of physical systems-Much of what is predicted is counter intuitive-Every counter intuitive prediction has been verified by subsequent experiments

Preview• Mathematical models of the physical world:

Quantum Theory• Observations

-Quantum theory may be more than a way of modeling the physical world… it may be a more accurate representation of reality than the physical objects we currently believe to exist-Quantum theory may be an imperfect representation of a physical world that we don’t yet understand-Our applications of quantum theory and the resulting predictions may, themselves, be naïve and imperfect

Preview

• Mathematical models of the physical world:

Quantum Theory• Observations

“If you think you understand this stuff… then you need to think about it some more”

Preview

• Mathematical models of the physical world:

Quantum Theory• The Schrodinger wave equation: - i h (d/dt) [phi] = 2 (pi) H [phi]

Preview

• Mathematical models of the physical world:

Quantum Computer (concept)• Let [phi] be selected (caused) to represent the

input data to a desired computation. Let the evolution of [phi] according the the Schrodinger equation, represent a computation we wish to perform. Let the outcome of a selected measurement, performed on the system after it has evolved, represent the output data we desire to compute (I.e., the solution).

Preview• Mathematical models of the physical world:

Quantum bit: QuBit (concept)

Let [phi1] and [phi2] represent the eigenstates of a simple 2-state quantum system. Then, one can represent any system state as:

a[phi1] + b [phi2] For this simple 2-state system, the particular

state: a=1 b=0 could represent one of two binary

conditions; while a=0 and b=1 could represent the other

Preview• Mathematical models of the physical world:

Quantum bit: QuBit (concept)

We need to create the quantum computer equivalents of logic gates. With the appropriate quantum logic gates we can build a quantum computer that can emulate any classical digital computer that can be built with classical logic gates.