> Amiga called the left and right brackets 'bra' and 'ket' which I always thought was clever. Wouldn’t know about Amiga, but this is standard notation in quant

> Amiga called the left and right brackets 'bra' and 'ket' which I always thought was clever. Wouldn’t know about Amiga, but this is standard notation in quantum mechanics (though you may be aware of this already). <φ| is a ‘bra’, and |ψ> is a ket — the two are adjoints of each other. Naturally, <φ|ψ> is a ‘braket’. (As my QM lecturer is fond of saying, ‘Dirac invented both the notation, and the pun’.)