Our team has created a new quantum bit, or qubit
by merging the spin of a single atom in silicon
with a strong oscillating electromagnetic field.
It's called a ‘dressed qubit’ – a qubit dressed by the field.
The dressed qubit retains quantum information much longer than the standard spin qubit.
That is a big advantage for us when we want to build a reliable quantum computer in silicon.
The qubit is the special carrier of information that we use to create, for example, entangled states,
which are the peculiar, purely quantum
computer code we need to use to unlock
the powerful parallel processing power of quantum computers.
But the quantum information encoded in the qubit can be fragile.
The longer we can hold on to that information, the more powerful computation we're able to perform.
Our single atom spin qubits in silicon are already very robust.
They are among the best
in the world.
But with the new dressed qubit,
we have succeeded in extending the life span of the information encoded in the qubit,
by yet another factor of 10.
To create the dressed qubit, we subject the electron spin to a strong, continuously oscillating
electromagnetic field at microwave frequencies.
This redefines the quantum bit as the orientation of the qubit
with respect to the oscillating
electromagnetic field.
We can control the dressed qubit by simply modulating the frequency of the microwave field,
just like you would broadcast a voice
through an FM radio channel.
By comparison, the undressed qubit requires turning the amplitude of the control fields on and off
a bit like an AM radio, which is more susceptible to noise and external disturbances.
This result gives us a new tool to create
a powerful and reliable quantum processor in silicon
using standard fabrication methods
as used for everyday computers.
