TELEPORTRTIOH 67
the future of the world's economy may one day depend on such computers, so there is enormous commercial interest in these technologies. One day Silicon Valley could become a Rust Belt, replaced by new
technologies emerging from quantum computing.
Ordinary computers compute on a binary system of Os and Is,
called bits. But quantum computers are far more powerful. They can
compute on qubits, which can take values between 0 and 1. Think of
an atom placed in a magnetic field. It is spinning like a top, so its spin
axis can point either up or down. Common sense tells us that the spin
of the atom can be either up or down but not both at the same time. But
in the strange world of the quantum, the atom is described as the sum
of two states, the sum of an atom spinning up and an atom spinning
down. In the netherworld of the quantum, every object is described by
the sum of all possible states. (If large objects, like cats, are described
in this quantum fashion, it means that you have to add the wave function of a live cat to that of a dead cat, so the cat is neither dead nor alive,
as I will discuss in greater detail in Chapter 13.)
Now imagine a string of atoms aligned in a magnetic field, with the
spin aligned in one fashion. If a laser beam is shone on this string of
atoms the laser beam will bounce off this collection of atoms, flipping
the spin axis of some of the atoms. By measuring the difference between the incoming and outgoing laser beam, we have accomplished
a complicated quantum "calculation," involving the flipping of many
spins.
Quantum computers are still in their infancy. The world's record
for a quantum computation is 3 x 5 = 15, hardly a calculation that will
supplant today's supercomputers. Quantum teleportation and quantum computers both share the same fatal weakness: maintaining coherence for large collections of atoms. If this problem can be solved, it
would be an enormous breakthrough in both fields.
The CIA and other secret organizations are intensely interested in
quantum computers. Many of the world's secret codes depend on a
"key," which is a very large integer, and one's ability to factor it into
prime numbers. If the key is the product of two numbers, each with
the future of the world's economy may one day depend on such computers, so there is enormous commercial interest in these technologies. One day Silicon Valley could become a Rust Belt, replaced by new
technologies emerging from quantum computing.
Ordinary computers compute on a binary system of Os and Is,
called bits. But quantum computers are far more powerful. They can
compute on qubits, which can take values between 0 and 1. Think of
an atom placed in a magnetic field. It is spinning like a top, so its spin
axis can point either up or down. Common sense tells us that the spin
of the atom can be either up or down but not both at the same time. But
in the strange world of the quantum, the atom is described as the sum
of two states, the sum of an atom spinning up and an atom spinning
down. In the netherworld of the quantum, every object is described by
the sum of all possible states. (If large objects, like cats, are described
in this quantum fashion, it means that you have to add the wave function of a live cat to that of a dead cat, so the cat is neither dead nor alive,
as I will discuss in greater detail in Chapter 13.)
Now imagine a string of atoms aligned in a magnetic field, with the
spin aligned in one fashion. If a laser beam is shone on this string of
atoms the laser beam will bounce off this collection of atoms, flipping
the spin axis of some of the atoms. By measuring the difference between the incoming and outgoing laser beam, we have accomplished
a complicated quantum "calculation," involving the flipping of many
spins.
Quantum computers are still in their infancy. The world's record
for a quantum computation is 3 x 5 = 15, hardly a calculation that will
supplant today's supercomputers. Quantum teleportation and quantum computers both share the same fatal weakness: maintaining coherence for large collections of atoms. If this problem can be solved, it
would be an enormous breakthrough in both fields.
The CIA and other secret organizations are intensely interested in
quantum computers. Many of the world's secret codes depend on a
"key," which is a very large integer, and one's ability to factor it into
prime numbers. If the key is the product of two numbers, each with