if we implement java interpreter in hardware then how we can achieve architecture neutrality of java bytecode... does java uses JIT(just in time interpreter) ? and how all this is related to Virtual Machine concept of operating system and java virtual machine(JVM)
There has already been several hardware implementations of the Java system (i.e. a CPU that can execute bytecodes) but they have not become mainstream. This is most likely because that software implementations perform as well or even better as CPU's have become faster and faster.
As you will find when investigating more thouroughly, the details of the JVM implementations are not that important (and vary quite a bit) but they all execute the machine language of the JVM - java byte code. If you stay within the Java world and do not link in "native" stuff, you should be fine with whatever implementation you choose.
This company makes a living of providing server systems tuned for Java programs, they might interest you: http://www.azulsystems.com/