Edit....actually the document below doesn't contain the phrase "EM" drive. Does mention research
on quantum vacuum (Dirac Sea). And is the lab and scientist referenced by the site linked earlier.
What NASA has to say about the EM drive can be found here...
NASA Technical Reports Server (NTRS) - Eagleworks Laboratories: Advanced Propulsion Physics Research
A link to the full text pdf there as well. A bit too big to attach, 800kb.
Since the work being pursued by this laboratory is applied scientific research
in the areas of the quantum vacuum, gravitation, nature of space-time, and other fundamental physical phenomenon, high fidelity testing facilities are needed. The lab will first implement a low-thrust torsion pendulum (<1 uN), and commission the facility with an existing Quantum Vacuum Plasma Thruster. To date, the QVPT line of research has produced data suggesting very high specific impulse coupled with high specific force. If the physics and engineering models can be explored and understood in the lab to allow scaling to power levels pertinent for human spaceflight, 400kW SEP human missions to Mars may become a possibility, and at power levels of 2MW, 1-year transit to Neptune may also be possible.