Consciousness (noun) the state of awareness of oneself, alertness and wakefullness.

The problem with consciousness is that it seemingly cannot be defined. Every attempt to do so ends up relying on other words such as "self-awareness" - which is actually not much more than a synonym.

The best description I've managed to come up with is this: "The state exhibited by the human brain when it is not damaged, resting, sedated or otherwise incapacitated".
And even so I'm implicitly discarding the possibility that I'm the only human that is conscious - see solipsism.

This description leaves a lot to be desired, of course - and it seems to actively exclude AI.

But wait - if consciousness is merely the state of a physical object, could we then not simulate it, provided we had detailed enough information about the laws of physics (be they quantum theory, string theory or what have you) and a sufficiently powerful computer?

Let's say we could simulate the human brain in detail - would the simulated brain be conscious?

Before you answer this question, consider your possibilities:

NO means that there is a component of consciousness that lies outside physical reality but is still capable of affecting physical reality. Even though almost all major religions entertain ideas of 'non-physical reality', science knows of no such thing - nothing can break the laws of physics. In fact, if we accept the idea that the mind is somehow not of this world, then we must be prepared to accept the claims of every crank who claims to be able to build a perpetual motion machine or perform telekinesis.

YES means that there is nothing in the mind that cannot be explained trough the rules of biological, mechanical, electrical, quantum-mechanical or other theories. Since consciousness arises from these rules in the human brain, the same thing would also happen in a computer implementing the same rules.
The old argument that "a simulated rainstorm does not make one wet" simply does not hold true - to an object or observer inside the simulation the simulated rainstorm and the resulting simulated wetness is as real as it can be.
Unfortunately, if laws of physics behave like we think they do, free will is pretty much impossible and we're all predetermined - conscious or not. Some theories suggest quantum theory as a way around predeterminism. But even so, we have just replaced the jail of predeterminism with the non-control of complete randomness - unless we postulate that there is some extra-physical free will behind quantum events, and then we're back where we started.

Sadly, it looks like we won't be able to find the answer to this until we know a lot more about both the brain and physics and certainly not before we have a lot more powerful computers.