bit locker is old hat - self encrypting drives are already here
Bitlocker is about "data at rest", while homomorphic encryption is about data in process and SSL (for example) is about data in transit. At present nearly all server class hard drives are self encryping, and most consumer drives though it may not say so on the label. I am told that by the end of this year nearly all HDs and SSDS of all types wi) be. All Apple products have been for years. What's been missing is a standardized library, which now exists (OPAL) and a widely accepted API and user/OS interface, which is now in the process of being accepted - see the Drive Trust Alliance (http://drivetrust.org iirc)
An SED drive keeps all the data encrypted all the time using an internally generated 256 bit key. Another set of keys - passwords - can be set externally. Resetting the drive's internal key effectively erases the drive as brute force decryption would require millions of dollars worth of cpu time at present.