Does momentum increase with out of phase photons? This paper speculates that the EM drive produces thrust with out of phase photons:
http://scitation.aip.org/content/aip/journal/adva/6/6/10.1063/1.4953807
My question is this, do out of phase photons have more momentum than the same set of photons traveling in phase?
Edit: More specifically, I'm interested in whether all the force of the beam is applied in one direction, rather than half on the receiving and half on the sending.
 A: The momentum of the photon is $p=h\nu/c$, so it only depends on its frequency, not its phase. At constant frequency, all photons will have the same $p$ regardless of phase. 
A: I am not supporting or seconding any finding in the article. They appear to be just incoherent chatting. However the pressure excerted by a electromagnetic wave is 
$P_{rad}=\frac{I} {c}$
where I is the intensity of light and c is light velocity.  In case of totally reflecting surfaces this will be doubled. Here you can see that the pressure is not of one photon but of whole em wave and it is independent of frequency of photon. It is assumed that the em wave have very large number of photons. 
Now if you think of splitting this beam in a Michelson interferometer and overlap it again precisely you can introduce phase difference in the beam. If path difference between two arms is very small, you will see bright and dark fringes, this comes from interference and energy is merely shifted from one point to other point. At the dark portion 'photons' will interfere destructively and in bright parts they will interfere constructively. The momentum is governed by the spatial intensity distribution. Destructive interference means low momentum transfer. 
A: They are trying to explain the resonant cavity thrusters , controversial propelling engines.
It seems to me that the paper you quote confuses photons with light waves, attributing a real space wave nature to the photon. From their fig1:

Our reasoning is that when light waves combined with opposite phases, the photons do not vanish for nothing but continue propagating and carrying momentum. 

The light wave emerges from a confluence of photons, elementary particles described by quantum electrodynamics. Individually they have energy equal to h*nu and momentum h/lamda . That is all, there are no real phases measurable for an individual photon.
Momentum is a vector quantity and in a classical particle is uniquely defined in direction too. In a quantum mechanical particle where a wavefunction in space gives the probability density for the location of the "particle"  the uncertainty in the location spatially will give an uncertainty to the individual photon direction. True the photon does not "vanish", it changes direction  and manifests from the dark fringes to the bright fringes during interference.
This blog entry by Lubos helped me understand how the classical beam emerges from the quantum mechanical individual photons. Hand waving: the classical beam emerges from the addition in space of the individual photon complex wave functions , which carry the electromagnetic potential A information in their complex manifestation. As photon-photon interactions are much repressed the potentials in their complex form add spatially and all the various classical interference patterns appear. It is how the quantum mechanical position uncertainty is quantified mathematically, for the given frequency, which is not random but controlled by each photon's wave function; this generates the interference patterns , the addition of probability density amplitudes have the sinusoidal dependence, not the photon in space.
As others have observed in standing waves, by construction, the photon momenta  add up to zero  beam momentum, as the classical beam emerges from photons  propagating backwards and forwards . Any opening will destroy the balance and momentum will be carried off by the photons in the beam.
Their basic premise seems to be out dated and wrong, italics mine:

Field theory, when manipulating photons as virtual particles, has been subject to reservations, because its follows from perturbation theory.19,20 Instead, the old atomistic tenet makes sense to us by regarding the quanta of light as indivisible and indestructible basic building blocks of nature.

I am not commenting on whether the particular controversial drive works or not, but on the explanation offered by the authors assuming it does. From the wiki article there seems to be doubt on the experimental side too.
A: I am not completely sure, but I would say, it depends what is the exact phase structure of the entire beam. If I was trying to approach the problem, I would use wave formalism and analyze the phase profile vs time. Good question.
