Method for optically transmitting quantum-information useful data

Abstract

In the method for optically transmitting useful data by means of a laser from a transmitter to a receiver, the receiver is designed as a quantum computer, having superconducting circuits, operated close to the absolute temperature zero point and has a photodiode, while the transmitter has a laser diode and is operated at room temperature. By means of the laser diode of the transmitter, for preparing data transmission at the receiver a reference frequency signal is transmitted to the receiver as a free beam or via an optical waveguide for specifying the frequency of the spins of the electrons, which define the quantum dots or the qbits of the quantum computer of the receiver for a certain period of time, and subsequently, useful data are transmitted to the receiver by means of the laser of the transmitter for the certain period of time.

Description

[0001] Methods for the optical transmission of user data

[0002] The present invention relates to a method for the optical transmission of user data by means of a laser from a transmitter to a receiver.

[0003] Systems operating at low temperatures, for example in the millikelvin (mK) range or cryogenic range, particularly near absolute zero, are known from the prior art. Such systems are used, for example, in quantum computing. According to the prior art, a problem arises with long transmission lines when using reference signals for electrical control. These problems are compensated for by applying pre-distortions, which, however, requires considerable effort. Low-impedance impedance matching always results in high power consumption, while high-impedance mismatches can lead to distortions that can affect the system's performance.Particularly in the cryogenic temperature range, high power consumption should be avoided, as the desired low temperatures can no longer be provided if high power losses occur.

[0004] US patent A-2023 / 0059433 describes an arrangement for transmitting data by means of a laser from a transmitter operating at room temperature to a computer system operating in the millikelvin range that incorporates superconducting circuits.

[0005] The initialization and readout of the optical SPEN of a cavity-coupled qubit in a magnetic field is described in "SHELDON, Samuel J. [et al.] : Optical spin initialization and readout with a cavity-coupled quantum dot in an in-plane magnetic field. Status: June 22, 2022 URL: https: / / arxiv.org / pdf / 2206.11008vl".

[0006] Based on the aforementioned disadvantages of the prior art, the present invention aims to provide reference signals, particularly for systems with low temperatures, where the reference signals can be provided even with long supply lines and low power consumption.

[0007] The aforementioned problem is solved according to a first aspect of the invention by a method for the optical transmission of user data by means of a laser from a transmitter to a receiver, wherein the receiver is a quantum computer operated at low temperatures, preferably near absolute zero, and has a photodiode, and the transmitter has a laser diode and is operated at room temperature, a reference signal is sent to the receiver by means of the laser diode of the transmitter as a free beam or via an optical waveguide to specify the frequency of the spins of the electrons that define the quantum dots or the qubits of the quantum computer of the receiver for a certain period of time, and subsequently user data is sent to the receiver by means of the laser of the transmitter for the certain period of time.

[0008] A further aspect of the invention is the subject of claim 2, according to which the receiver is a quantum computer operating at near absolute zero and comprising at least one quantum dot or at least one qubit, and comprising a photodiode, and the transmitter comprises a laser diode and is operated at room temperature, by means of the laser diode of the transmitter, a reference frequency signal is sent to the receiver as a free beam or via an optical waveguide to stimulate the at least one quantum dot or the at least one qubit by specifying the frequency of the spins of the electrons that define the at least one quantum dot or the at least one qubit of the receiver's quantum computer for a specific period of time, and subsequently, by means of the laser diode of the transmitter, user data is sent to the receiver for its at least one quantum dot or the at least one qubit for the specified period of time.for which at least one qbit is sent.

[0009] The dependent claims relate to further embodiments of the invention according to both aspects.

[0010] The receiver may therefore be a system operating in the cryogenic range, such as, in particular, a part of a quantum computer containing superconducting circuits.

[0011] The reference signal can be symbol-based data, such as for implementing digital data transmission. Alternatively, the reference signals can be reference frequency signals, which are transmitted at defined times and prepare the qubits for data transmission.

[0012] The transmitter typically has an electrically controlled laser diode, and thus, more generally speaking, an electro-optical converter, while the receiver has, for example, a photodiode, or more generally speaking, an opto-electrical converter.

[0013] The laser beam can be transmitted through an optical conductor, such as a fiber optic cable. The photodiode can be operated at the lowest temperature of the system or at a higher temperature.

[0014] The laser beam can be generated at higher, i.e., at any operating temperature.

[0015] The photodiode can preferably be used with electrical biasing, whereby a defined bias voltage is applied to the photodiode. Particularly preferably, the photodiode can utilize only the power generated by the laser.

[0016] The photodiode can preferably be an InGaAs diode or a Si diode.

[0017] One embodiment of the invention comprises an arrangement such as that described, for example, in US-A-2023 / 0059433, the contents of which are hereby incorporated by reference into the subject matter of the present patent application. As can be seen from the aforementioned document, the arrangement described therein serves to transmit data by means of a laser from a transmitter operating at room temperature to a computer system operating in the millikelvin range, which incorporates superconducting circuits. According to the invention, this system is further enhanced by transmitting reference signals, and in particular reference frequency signals (i.e., signals containing reference frequencies), prior to the actual data transmission for the stimulation of quantum dots or qubits of the receiver. According to the invention, these reference frequency signals are transmitted via the same optical channel that is subsequently used for the actual data transmission.

[0018] The invention is therefore characterized in that the laser and the photodiode, i.e. the electro-optical converter of the transmitter and the opto-electrical converter of the receiver, are used for the transmission of the reference frequency signals, both of which are also used for the actual data transmission, as is not the case with the system according to the above-mentioned publication.

Claims

Patent claims 1. Method for the optical transmission of user data by means of a laser from a transmitter to a receiver, wherein - the receiver is a quantum computer operating at near absolute zero temperature, having at least one quantum dot or at least one qubit, and a photodiode, and the transmitter has a laser diode and operates at room temperature, - by means of the transmitter's laser diode, a reference frequency signal is sent to the receiver as a free beam or via an optical waveguide to specify the frequency of the electron spins that define the at least one quantum dot or the at least one qubit of the receiver's quantum computer for a specific period of time. - subsequently, data is sent to the receiver via the transmitter's laser diode for a specified period of time.

2. The method according to claim 1, characterized in that - the receiver is a quantum computer operating at near absolute zero temperature, having at least one quantum dot or at least one qubit, and a photodiode, and the transmitter has a laser diode and operates at room temperature, - by means of the transmitter's laser diode, a reference frequency signal is sent to the receiver as a free beam or via an optical waveguide to stimulate the at least one quantum dot or the at least one qubit by specifying the frequency of the electron spins that define the at least one quantum dot or the at least one qubit of the receiver's quantum computer for a specific period of time. Subsequently, by means of the transmitter's laser diode, user data is sent to the receiver for the specified period of time for its at least one quantum dot or for its at least one qubit.

3. Method according to claim 1 or 2, characterized in that the reference frequency signal is generated by encoding using one or more microwave pulses.

4. Method according to one of claims 1 to 3, characterized in that the reference frequency signal is used to control a superconducting quantum dot or qubit.