/Tag: polarization

Quantum Cheshire Cat and Resurrection

In memory of my father, Abraham Shamshin ben Reuven, ע"ה   For those of us who can't get enough of Schrödinger cat, comes a new feline—Quantum Cheshire Cat—the creation of an Israeli physicist, Yakir Aharonov. In Alice in Wonderland, Alice meets a grinning Cheshire cat. To her amazement, the cat disappears leaving only his grin behind: "All right', said the Cat; and this time it vanished quite slowly, beginning with the end of the tail, and ending with the grin, which remained some time after the rest of it had gone. Well! I've often seen a cat without a grin, but a grin without a cat! It's the most curious thing I ever saw in my life!" According to Martin Gardner, the statement "a grin without a cat" is a reference to mathematics dissociating itself [...]

Pesach Sheini – in a State of Superposition

In physics, we speak of systems and states. A system is a collection of physical objects (particles, waves, etc.). A system can be in various states. For example, a coin could have two states—heads or tails. A top also has two possible states—it can be spinning clockwise or counterclockwise. Light can have two states as well—being in the vertical polarization or horizontal polarization. In classical mechanics, a system can only be in a single state, i.e., at any given point in time, a coin can be either in a state “Heads” or in the alternative state “Tales”. A top can either be spinning clockwise or counterclockwise. In quantum mechanics, a system can also be in a state of superposition. Let us say, the system has two possible states A and B. If a [...]