Jacques Vallee emphasized the importance of trying to overcome the light barrier for star ship technology with quantum entanglement in the first meeting of the joint DARPA-NASA 100 Year Star Ship workshop in January 2011 in Marin County. MIT physics historian David Kaiser describes how this idea came about and objections to it in his book “How The Hippies Saved Physics” (W.W. Norton, New York, 2011). Mainstream opinion is that the direct use of quantum entanglement as a C3 command, control, and communication channel without a light-speed limited signal “key” is fundamentally impossible because of the linearity of observable operators and the unitarity of quantum state time evolution between strong measurements. Aharonov has introduced new kinds of weak measurements that need both pre and post-selection. Unitarity of quantum time evolution operator , where the Hamiltonian is Hermitian with real energy eigenvalues, is the crux of the claim of Susskind and ‘t Hooft against Hawking that information is not lost behind the event horizon of an evaporating black hole. Hawking caved in to Susskind, but perhaps he should have held his ground. Cosmological horizons will also evaporate of course, but over an enormous time scale. Observers are outside black hole horizons, but inside cosmological horizons. It is also claimed that energy would not be conserved with non-unitary time evolution. This is debatable. It’s a pyrrhic victory because the observer must wait over many aeons to recover the lost information from the evaporating horizon. Information is lost in any real practical operational measurement sense over durations short compared to the observer’s life span.
Unitarity of the time evolution of micro-quantum states implies that total probability is strictly conserved. However, would mean that new order at lower energy large scales could not emerge. That is the space of possible outcomes is fixed in the unitarity approximation. Therefore, the Sacred Cow of unitarity is shaky ground on which the no-entanglement signaling theorems rest. John Cramer has also questioned this assumption within orthodox quantum theory.  The act of measurement in orthodox quantum theory is non-unitary and may be a loophole overlooked in the accepted no-signaling theorems. Beyond that is the suggestion that orthodox quantum theory is not the final theory of physical reality, but is an approximation to a more general theory in the same way that Einstein’s 1905 special theory of relativity is an approximation to his 1916 general theory of relativity. Special relativity only works in globally flat Minkowski spacetime with zero curvature, which, in fact does not exist in the real world except approximately locally on a scale small compared to the radii of curvature. General relativity deals with the invariants of momentarily coincident local frame detectors all measuring the same actual test particles. Test particles are not sources of gravitational field. They are acted on, but do not act. That is an approximation, but a good one in practice. In particular, Einstein’s strong equivalence principle deals with the particular transformations between non-rotating local inertial frames (LIFs) on timelike geodesics with zero g-force registered on their accelerometers on the one hand, and possibly rotating local non-inertial frames (LNIFs) whose centers of mass need not be on timelike geodesics. Off-geodesic LNIFs require a non-gravity g-force to push them off their natural geodesic. Indeed, the Levi-Civita connection field in Einstein’s theory describes the non-gravity g-forces on the detector not actual forces on the test particle that is being measured. For example, a rocket engine must fire to hover at fixed distance from the event horizon of a black hole. The crew feels artificial gravity from the electrical reaction force of the metal fuselage on them. Since curvature is a tensor, if it does not vanish in one local frame, it will not vanish in any other momentarily coincident local frame either LNIF or LIF.
Antony Valentini  has used Bohm’s “quantum potential” with real particles to model such a general quantum theory with “signal nonlocality” that would allow instantaneous interstellar communications as described in David Kaiser’s book based on this author’s ideas from the 1970’s and later. Valentini wrote:
“It is argued that immense physical resources - for nonlocal communication, espionage, and exponentially-fast computation - are hidden from us by quantum noise, and that this noise is not fundamental but merely a property of an equilibrium state in which the universe happens to be at the present time. It is suggested that 'non-quantum' or nonequilibrium matter might exist today in the form of relic particles from the early universe. We describe how such matter could be detected and put to practical use. Nonequilibrium matter could be used to send instantaneous signals, to violate the uncertainty principle, to distinguish non-orthogonal quantum states without disturbing them, to eavesdrop on quantum key distribution, and to outpace quantum computation (solving NP-complete problems in polynomial time).”
Just as Einstein’s general relativity uses test particles that are acted on but do not act as sources of the gravitational field, so too David Bohm  showed that orthodox quantum theory’s “no-signaling” theorems also assume that electrons, atoms, molecules et-al are also test particles that are acted on but do not act as sources of their guiding quantum potential that contains the entanglement to other test particles. Another way to look at Valentini’s model is that when the particle “hidden variables” are no longer test particles, but also act as sources of their own and other test particle’s common entangled quantum potential, that they then form emergent self-organizing feedback-control loops with a breakdown of the no-signal theorems. When can this be expected this to happen?  Soft condensed matter physics relies on the same kind of “More is different”  spontaneous symmetry breaking emergent order in the ground state of real on-mass-shell particles outside the vacuum that we see in the Higgs-Goldstone macro-quantum Glauber coherent states  of off-mass-shell virtual particles inside the vacuum that is so important in both large-scale inflationary cosmology as well as in the standard model of flavor symmetry breaking in the weak force giving small rest masses to leptons and quarks as well as larger rest masses to the W-bosons. Indeed, there is also a kind of color spontaneous symmetry breaking in the quantum chromodynamics of the much larger hadron bound states of real quarks with virtual gluons that Frank Wilzcek  calls the “multi-layered multi-colored vacuum superconductor” of virtual gluon and virtual quark-antiquark pair Bose-Einstein condensates. Spontaneous symmetry breaking means that the global dynamical action and its local Euler-Lagrange quantum field equations have the full continuous symmetries, but their lowest energy state does not. Examples include ordinary crystals that spontaneously break the 3D continuous translation group leaving only the discrete groups of 19th Century crystallography. The phonon is the massless Goldstone quantum. Other examples involving different symmetry groups are ferromagnets, ferroelectrics, liquid crystals, superconductors, superfluid helium and possibly the macro-quantum coherent field in our brain responsible for both sub-conscious and conscious mental activity. This far-from-thermodynamic equilibrium dissipative structure macro-quantum coherent field is acted upon by neuroelectrical and neurochemical signals and also acts back on them in highly nonlinear self-organizing ways.  It is here where signal nonlocality is predicted to emerge. Indeed, Landau and Ginzburg developed the theory of these effects.  The emergent low energy dynamics is nonlinear in contrast to micro-quantum theory, it is also nonunitary in contrast to micro-quantum theory, and the c-number macro-quantum coherent field is local in ordinary space-time in contrast to the nonlocal entanglement of micro-quantum theory. Coherent states including squeezing are not orthogonal like sharp number Fock micro-quantum states are. This may provide another loophole to the no-entanglement signal theorems if the degree of non-orthogonality at the sender can be modulated it will affect the response of the entangled receiver. In spite of this emergent locality spatially separated coherent states can still, it appears, be entangled in a way largely immune from thermal decoherence.  Of course the micro-quantum particles jump into and out of the coherent field in a random way according to the usual orthodox quantum rules. That is, we have random micro-quantum noise coupled to non-random macro-quantum signal. The basic Born probability rules only apply to the noise not to the signal that has a robust “phase rigidity” making it immune to environmental decoherence especially when there are anyonic-braid topological restrictions in 2D “quantum well” nano-tech membrane layers made, for example, from graphene sheets.