Quantum Dot Photon Source Timing Jitter Control
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Solution Overview
Problem
Existing single photon sources have high jitter in photon emission time due to radiative decay time limitations, which restricts their operating frequency and efficiency in quantum communication and computing applications.
Innovation Solution
A photon source with a quantum dot structure that allows controlled carrier injection and state change after a predetermined time, reducing jitter by switching carriers into an optically 'dark' state or separating charges, using electrical or optical excitation with complex pulse sequences to mitigate photon 'bunching and anti-bunching effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carriers are allowed to recombine naturally in the quantum dot, then photon emission occurs, but the emission time has high jitter limited by radiative decay time
Solution Approach 1:
The patent applies preliminary action by changing the state of carriers in the quantum dot before they naturally recombine. A control signal is applied to switch carriers into an optically dark state or separate them before radiative recombination would occur, thereby preventing photon emission at unpredictable times and reducing timing jitter
Solution Approach 2:
The patent changes the physical state of carriers in the quantum dot by applying control signals that modify carrier configuration. This parameter change switches carriers between optically active and dark states, enabling precise control over when radiative recombination occurs and thus improving emission timing precision
2Speed
If the radiative decay time is reduced to increase operating frequency, then speed improves, but the fundamental limit of radiative decay cannot be overcome
Solution Approach 1:
The patent uses preliminary action to prevent carriers from undergoing natural radiative recombination by switching them to dark states before recombination occurs. This allows the system to operate at frequencies higher than the natural radiative decay rate while maintaining reliable emission timing through controlled state changes
Solution Approach 2:
The patent employs periodic control signals to repeatedly switch carriers into and out of dark states, enabling operation at frequencies determined by the control signal period rather than the natural radiative decay time. This periodic modulation allows high-speed operation with reliable timing control
3Productivity
If carriers are held in the quantum dot for extended periods, then more photons can be emitted, but jitter increases and photons become indistinguishable
Solution Approach 1:
The patent uses periodic control signals to rhythmically switch carriers between active and dark states, enabling high photon emission rates through repeated cycles of controlled recombination. This periodic modulation ensures each photon is emitted at a predictable time, maintaining indistinguishability while increasing overall productivity
Solution Approach 2:
The patent changes the optical state parameter of carriers through control signals, switching them between states that allow and forbid radiative recombination. This parameter control enables high emission rates while maintaining photon indistinguishability by ensuring all photons are emitted under identical controlled conditions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the uncertainty in photon emission time, enabling higher speed operation and improved efficiency for generating indistinguishable photons and synchronized quantum communication and computing.
Implementation Method 1
electrons and holes are either optically or electrically injected into a quantum dot. The injected carriers then recombine to emit photons
Implementation Method 2
moving the carriers into an optically 'dark' state (Note: an optically 'dark' state is a state in which the configuration of the spins in the quantum dot is such that radiative recombination is forbidden under the rules of quantum mechanics)
Data Source
AI summary
A photon source comprising a photon source body, said photon source body comprising at least one quantum dot; carrier injection means for injecting carriers into said at least one quantum dot and change of state means for changing the state of the carriers within the quantum dot after a predetermined time duration, the carrier injection means injecting carriers which are configured to allow emission of radiation by radiative recombination.