In quantum computing, the **cat state**, named after Schrödinger's cat, is the special quantum state where the qubits are in an equal superposition of all being |0> and all being |1>, i.e. (in Bra-ket notation): |00...0> +|11...1>.

In other quantum mechanics contexts, according to *The New York Times* for example, physicists view the cat state as composed of two diametrically opposed conditions *at the same time*, such as the possibilities that a cat be alive and dead at the same time. This is sometimes called the many worlds hypothesis. More prosaically, a cat state might be the possibilities that six atoms be *spin up* and *spin down*, as published by a team at NIST, December 1, 2005. This spin up/down formulation was proposed by David Bohm, who conceived of spin as an observable in a version of thought experiments formulated in the 1935 EPR paradox. David Bohm and Yakir Aharonov later attained recognition for the Aharonov-Bohm effect, 1959.

Erwin Schrödinger formulated this concept by positing a condition in which one intrinsically does not know something, and that only by performing an observation could one know it. He dramatized the situation by positing a moral choice (bestowing life or death on a cat). Later formulations have de-emphasized the life/death choice by showing the possibility of a cat state which is independent of human action.

Read more about Cat State: In Quantum Optics

### Other articles related to "cat state, states, state, cat, cat states":

**Cat State**- In Quantum Optics

... In quantum optics, a

**cat state**is defined as the coherent superposition of two coherent

**states**with opposite phase , where , and , are coherent

**states**defined in ... Notice that if we add the two

**states**together, the resulting

**cat state**only contains even Fock

**state**terms ... As a result of this property, the above

**cat state**is often refereed to as an even

**cat state**...

... These experiments do not show that a

**cat**-sized object can be superposed, but the known upper limit on "

**cat states**" has been pushed upwards by them ... In many cases the

**state**is short-lived, even when cooled to near absolute zero ... A "

**cat state**" has been achieved with photons ...

### Famous quotes containing the words state and/or cat:

“The stars which shone over Babylon and the stable in Bethlehem still shine as brightly over the Empire *State* Building and your front yard today. They perform their cycles with the same mathematical precision, and they will continue to affect each thing on earth, including man, as long as the earth exists.”

—Linda Goodman (b. 1929)

“How they got a *cat* up there I do not know, for they are as shy as my aunt about entering a canoe. I wondered that she did not run up a tree on the way; but perhaps she was bewildered by the very crowd of opportunities.”

—Henry David Thoreau (1817–1862)