Quantum
Information Research at NIST: Goals and Vision
What
Good Is Quantum Information?
What
is Quantum Information?
Quantum
Computing
Quantum
Communications
Selected
NIST publications
Contact
information |
Quantum
Information Theory
 |
Mathematician Anastase Nakassis
developed the error-correction method for NIST's quantum key distribution
system.
©Robert Rathe |
Quantum information
provides a powerful new model for information processing, but its capabilities
have yet to be fully understood and are also open to misinterpretation.
To transform today’s experimental components into reliable, well-engineered
computers and communications systems, theoretical research is needed.
In much the same way that John von Neumann created the architecture
still used to build classical computers—the four main parts are
the processor, control unit, memory, and input/output devices—information
theorists are beginning to create the paradigm for quantum systems.
Questions to be
answered include: What fundamental operations are needed for the central
processing unit? How should hundreds of logic operations be connected
so they interact smoothly? What basic programming is needed for the
central processing unit? How can efficient quantum circuits be created
on the fly? What are the best error-correction techniques and how can
they be efficiently implemented? How does one move information in a
quantum computer without wires? What quantities can, or cannot, be
computed more efficiently on a quantum computer than on a classical
computer? And, what algorithms will translate the output (ordinary
1s and 0s) into meaningful results that reflect the inherent quantum
parallel processing involved?
For quantum communications:
Is quantum cryptography really “unbreakable”? Can it ever
work fast and reliably enough, at sufficiently low cost, for widespread
use?
NIST contributions
to quantum information theory include:
- An error-correction
architecture that could make quantum computers much easier to build
than previously imagined. The NIST architecture would enable reliable
computing even if individual logic operations made small errors as
often as 3 percent of the time—performance levels already achieved
at NIST with atomic-ion traps. The proposed architecture could tolerate
error rates several hundred times larger than scientists had generally
thought acceptable.
- A “communications
bus” scheme allowing distant qubits in a quantum computer to
communicate as if they were in direct contact. Imagine a transit
bus that instantly transports commuters to their destination. Rather
than passing data through a long line of qubits in between, the NIST
scheme would create a chain of entangled pairs of empty “bus
qubits” between two distant memory qubits that need to exchange
information. Then the ends of the chain would be entangled with each
other. This entanglement can be used to perform joint operations
on qubits near opposite endpoints, in ways that increase processing
speed and reduce errors.
- An analysis of
security vulnerabilities suggesting that some implementations of
quantum cryptography are not really “unbreakable.” The
analysis shows that some eavesdropping approaches could break an
encryption scheme that relies on manipulation and return of entangled
qubits to create a shared “key.” This suggests that,
at least in some cases, quantum cryptography can be vulnerable to
attacks not envisioned by system designers. The history of cryptography
is full of examples of approaches that were believed to be secure
but shown to be vulnerable to novel attacks, often years after their
design.
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