Download Lecture 1

Quantum Information Science
and Technology (QuIST)
Stewart D. Personick (sdp)
[email protected]
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
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
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;
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.