Figure 3
From: Entanglement concentration for arbitrary four-particle linear cluster states
Schematic drawing of PCD operated on the original particle 1 and the ancillary particle 1′35. ±θ represents that cross-Kerr nonlinearity makes |α〉 into |αe ±iθ〉 when there is a particle passing. The even-parity states |HH〉 and |VV〉 will introduce phase shift ±θ to |α〉, while the odd-parity states |HV〉 and |VH〉 result in no phase shift. |χ〉〈χ| is the homodyne measurement that can distinguish different phase shifts.
