Unpolarized light (such as the light from an incandescent light bulb) cannot be described as any state of the form α α | R ⟩ ⟩ + β β | L ⟩ ⟩ (linear, circular, or elliptical polarization). Unlike polarized light, it passes through a polarizer with 50% intensity loss whatever the orientation of the polarizer; and it cannot be made polarized by passing it through any wave plate. However, unpolarized light can be described as a statistical ensemble, e. g. as each photon having either | R ⟩ ⟩ polarization or | L ⟩ ⟩ polarization with probability 1/2. The same behavior would occur if each photon had either vertical polarization | V ⟩ ⟩ or horizontal polarization | H ⟩ ⟩ with probability 1/2. These two ensembles are completely indistinguishable experimentally, and therefore they are considered the same mixed state. For this example of unpolarized light, the density operator equals