A UNSW-led research team has encoded quantum information in silicon using simple electrical pulses for the first time, bringing affordable large-scale quantum computers one step closer to reality.
The team has already improved the control of these qubits to an accuracy of above 99% and established the world record for how long quantum information can be stored in the solid state.
The method of qubit control demonstrated here fulfills all the practical requirements for a large-scale quantum computer, because control gates can be applied simultaneously to arbitrarily many qubits while requiring only one CW microwave source together with inexpensive multichannel baseband pulse generators.
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Electron wave in a phosphorus atom, distorted by a local electric field.
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Electric field dependence of electron and nuclear energy states. (A) False-colored scanning electron microscope image of a device similar to the one used in the experiment. Blue, microwave (MW) antenna; yellow, gates used to induce the SET charge sensor under the SiO2 insulator; pink, A-gates, comprising gates labeled Donor Fast (DF), Donor Slow (DS), and Top Gate AC (TGAC). These gates are used to tune the potential and electric field at the donor location. (B) Electron wavefunction of a donor under an electrostatic gate. A positive voltage applied to the gate attracts the electron toward the Si-SiO2 interface. For illustration purposes, the wavefunction distortion is largely exaggerated as compared to the actual effect taking place in the experiment. (C) Energy level diagram of the neutral e−-31P system. Gate-controlled distortion of the electron wavefunction modifies A and γe, shifting the ESR νe1 and νe2, and the NMR νn1 and νn2 transition frequencies.
Science Advances - Electrically controlling single-spin qubits in a continuous microwave field
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The team has already improved the control of these qubits to an accuracy of above 99% and established the world record for how long quantum information can be stored in the solid state.
The method of qubit control demonstrated here fulfills all the practical requirements for a large-scale quantum computer, because control gates can be applied simultaneously to arbitrarily many qubits while requiring only one CW microwave source together with inexpensive multichannel baseband pulse generators.
Electric field dependence of electron and nuclear energy states. (A) False-colored scanning electron microscope image of a device similar to the one used in the experiment. Blue, microwave (MW) antenna; yellow, gates used to induce the SET charge sensor under the SiO2 insulator; pink, A-gates, comprising gates labeled Donor Fast (DF), Donor Slow (DS), and Top Gate AC (TGAC). These gates are used to tune the potential and electric field at the donor location. (B) Electron wavefunction of a donor under an electrostatic gate. A positive voltage applied to the gate attracts the electron toward the Si-SiO2 interface. For illustration purposes, the wavefunction distortion is largely exaggerated as compared to the actual effect taking place in the experiment. (C) Energy level diagram of the neutral e−-31P system. Gate-controlled distortion of the electron wavefunction modifies A and γe, shifting the ESR νe1 and νe2, and the NMR νn1 and νn2 transition frequencies.
Science Advances - Electrically controlling single-spin qubits in a continuous microwave field
Read more »
