Quantencomputer
NSA seeks to build quantum computer that could crack most types of encryption
Barton Gellman DEC 24
His leaks have fundamentally altered the U.S. government’s relationship
with its citizens, the rest of the world.
Full coverage: NSA Secrets
Image
Read all of the stories in The Washington Post’s ongoing coverage of the
National Security Agency’s surveillance programs.
"If you think you understand quantum mechanics, you don't understand
quantum mechanics," said the late Nobel laureate Richard Feynman, widely
regarded as the pioneer in quantum computing. The science video blog
Vertiasium tries to help make sense of it.
[Read an annotated description of the Penetrating Hard
Targets project]
The development of a quantum computer has long been a goal of many in
the scientific community, with revolutionary implications for fields
such as medicine as well as for the NSA’s code-breaking mission. With
such technology, all current forms of public key encryption would be
broken, including those used on many secure Web sites as well as the
type used to protect state secrets.
Physicists and computer scientists have long speculated about whether
the NSA’s efforts are more advanced than those of the best civilian
labs. Although the full extent of the agency’s research remains unknown,
the documents provided by Snowden suggest that the NSA is no closer to
success than others in the scientific community.
“It seems improbable that the NSA could be that far ahead of the open
world without anybody knowing it,” said Scott Aaronson, an associate
professor of electrical engineering and computer science at the
Massachusetts Institute of Technology.
The NSA appears to regard itself as running neck and neck with quantum
computing labs sponsored by the European Union and the Swiss government,
with steady progress but little prospect of an immediate breakthrough.
“The geographic scope has narrowed from a global effort to a discrete
focus on the European Union and Switzerland,” one NSA document states.
Seth Lloyd, an MIT professor of quantum mechanical engineering, said the
NSA’s focus is not misplaced. “The E.U. and Switzerland have made
significant advances over the last decade and have caught up to the U.S.
in quantum computing technology,” he said.
The NSA declined to comment for this article.
The documents, however, indicate that the agency carries out some of its
research in large, shielded rooms known as Faraday cages, which are
designed to prevent electromagnetic energy from coming in or out. Those,
according to one brief description, are required “to keep delicate
quantum computing experiments running.”
[Read a document describing classification levels related to quantum
computing efforts]
The basic principle underlying quantum computing is known as “quantum
superposition,” the idea that an object simultaneously exists in all
states. A classical computer uses binary bits, which are either zeroes
or ones. A quantum computer uses quantum bits, or qubits, which are
simultaneously zero and one.
This seeming impossibility is part of the mystery that lies at the heart
of quantum theory, which even theoretical physicists say no one
completely understands.