Superinductor-based remote entanglement coupler

Abstract

To provide a method of remote entanglement of alternating current (AC) dipoles.SOLUTION: A method includes: supplying a bias current to a tunable superinductor, inductively coupling a current from a first AC dipole into the tunable superinductor, and inductively coupling an induced current from the tunable superinductor into a second AC dipole.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] Aspects of the present disclosure relate to quantum sensing, and in particular to techniques for remote entanglement between quantum systems using superconducting components. [Background technology]

[0002]

[0002] Various technologies are used to provide alternating current (AC) dipoles, such as quantum dots and superconductors. Such quantum devices can hold a single electron and manipulate it to perform many quantum computing functions.

[0003]

[0003] One conventional solution for achieving remote entanglement of quantum devices relies primarily on superconducting cavity resonators. These resonators tend to be difficult to fabricate with a sufficient quality factor to achieve clean entanglement operations. Furthermore, these resonators cannot precisely tune their resonant frequencies and modes. For example, to generate certain standing wave configurations, electrodes are required to be central to reinforce the nodes of the resonant waveform to maximize entanglement. Furthermore, resonator operation relies on the transmission of single photons to transfer energy between entangled quantum devices. External noise from the environment or nearby electronics is the dominant failure mode. This dominant failure mode competes with the relatively weak coupling and can render the resonator inoperable, for example, by de-resonating quantum information. Summary of the Invention

[0004] In one aspect, the present disclosure provides a method for remote entanglement of alternating current (AC) dipoles, the method including providing a bias current to an adjustable superinductor, inductively coupling a current from a first AC dipole into the adjustable superinductor, and inductively coupling the induced current from the adjustable superinductor into a second AC dipole.

[0005]

[0005] In one aspect, in combination with any exemplary method described above or below, the method further includes providing a control signal to one or both of the first AC dipole and the second AC dipole to maximize the charge dipole between the first AC dipole and the second AC dipole.

[0006]

[0006] In one aspect, in combination with any of the above or below exemplary methods, a tunable superinductor comprises a superconducting quantum interference device (SQUID) and a direct current (DC) current source that provides a bias current.

[0007]

[0007] In one aspect, in combination with any of the exemplary methods described above or below, a first mutual inductor couples a first AC dipole to a first port of an adjustable super inductor, and a second mutual inductor couples a second AC dipole to a second port of the adjustable super inductor.

[0008]

[0008] In one aspect, in combination with any example method above or below, a tunable super inductor comprises a first branch coupling a first mutual inductor to a second mutual inductor. The first branch comprises one or more Josephson junctions (JJs) coupled in series. The tunable super inductor further comprises a second branch coupling the first mutual inductor to the second mutual inductor. The second branch comprises a SQUID and a DC current source.

[0009]

[0009] In one aspect, in combination with any of the exemplary methods described above or below, the second branch further comprises a third mutual inductor having an input port coupled to a DC current source, and the SQUID comprises a first JJ coupled in parallel with the series combination of the second JJ and the output port of the third mutual inductor.

[0010] In one aspect, in combination with any exemplary method above or below, the second branch further comprises one or more JJs coupled in series with the SQUID.

[0011] In one aspect, the present disclosure provides a system including a first alternating current (AC) dipole, a second AC charge dipole, and an entanglement circuit coupled to the first AC charge dipole and the second AC charge dipole, the entanglement circuit comprising a tunable super inductor.

[0012] In one aspect, in combination with any of the exemplary systems described above or below, a tunable superinductor comprises a superconducting quantum interference device (SQUID) and a direct current (DC) current source.

[0013]

[0013] In one aspect, in combination with any of the exemplary systems described above or below, the system further includes a first mutual inductor coupled to the first AC charge dipole and a first port of the entanglement circuit, and a second mutual inductor coupled to the second AC charge dipole and a second port of the entanglement circuit.

[0014] In one aspect, in combination with any exemplary system described above or below, a tunable super inductor comprises a first branch coupling a first mutual inductor to a second mutual inductor. The first branch comprises one or more Josephson junctions (JJs) coupled in series. The tunable super inductor further comprises a second branch coupling the first mutual inductor to the second mutual inductor. The second branch comprises a SQUID and a DC current source.

[0015]

[0015] In one aspect, in combination with any of the exemplary systems described above or below, the second branch further comprises a third mutual inductor having an input port coupled to a DC current source, and the SQUID comprises a first JJ coupled in parallel with the series combination of the second JJ and the output port of the third mutual inductor.

[0016] In one aspect, in combination with any of the above or below described exemplary systems, the second branch further comprises one or more JJs coupled in series with the SQUID.

[0017]

[0017] In one aspect, in combination with any of the exemplary systems described above or below, a DC current source is configured to supply a bias current to the input port, the value of the bias current being selected to maximize coupling between the first AC charge dipole and the second AC charge dipole.

[0018] In one aspect, the present disclosure provides an apparatus including a first port coupled to a first alternating current (AC) dipole, a second port coupled to a second AC dipole, and a tunable superinductor coupled to the first port and the second port.

[0019] In one aspect, in combination with any of the exemplary devices described above or below, a tunable superinductor comprises a superconducting quantum interference device (SQUID), and a direct current (DC) current source.

[0020]

[0020] In one aspect, in combination with any of the exemplary devices described above or below, the device further comprises a first mutual inductor coupled to the first AC charge dipole and the first port, and a second mutual inductor coupled to the second AC charge dipole and the second port.

[0021] In one aspect, in combination with any example apparatus described above or below, a tunable super inductor comprises a first branch coupling a first mutual inductor to a second mutual inductor. The first branch comprises one or more Josephson junctions (JJs) coupled in series. The tunable super inductor further comprises a second branch coupling the first mutual inductor to the second mutual inductor. The second branch comprises a SQUID and a DC current source.

[0022]

[0022] In one aspect, in combination with any of the exemplary devices described above or below, the second branch further comprises a third mutual inductor having an input port coupled to a DC current source, and the SQUID comprises a first JJ coupled in parallel with the series combination of the second JJ and the output port of the third mutual inductor.

[0023] In one aspect, in combination with any of the above or below described exemplary apparatus, the second branch further comprises one or more JJs coupled in series with the SQUID.

[0024]

[0024] So that the above-described features of the present disclosure can be understood in detail, a more detailed description of the present disclosure than that briefly summarized above can be made by reference to several exemplary embodiments, some of which are illustrated in the accompanying drawings. [Brief explanation of the drawings]

[0025] [Figure 1] 1 illustrates an exemplary quantum system, according to one or more aspects. [Figure 2]

[0026] 1 illustrates a system having an exemplary entanglement circuit, according to one or more embodiments. [Figure 3]

[0027] 1 illustrates an exemplary method for remote entanglement of alternating current (AC) dipoles, according to one or more embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0026]

[0028] The present disclosure relates to techniques for high-precision, tunable, electrically protected remote entanglement of alternating current (AC) dipoles. In some aspects, the remote entanglement method includes supplying a bias current to a tunable superinductor, inductively coupling a current from a first AC dipole into the tunable superinductor, and inductively coupling the induced current from the tunable superinductor into a second AC dipole. In some aspects, the tunable superinductor is based on a series of Josephson junctions, which exhibit large and tunable inductance (and impedance) and strong coupling.

[0027]

[0029] The use of tunable superinductors enables long-distance entanglement with greater tunability and greater separation of entangled quantum states than conventional solutions, such as cavity resonators combined with current transmission line technology. Beneficially, these high-precision, tunable, electrically protected remote entanglement techniques support further development of robust quantum sensing technologies, cryo-controlled electronics, and higher performance entanglement swapping. The remote entanglement techniques described herein also improve manufacturing uniformity.

[0028]

[0030] In the present disclosure, reference is made to various embodiments. However, it should be understood that the disclosure is not limited to the particular described embodiments. Instead, any combination of the following features and elements, whether associated with various embodiments or not, is contemplated for implementing and practicing the teachings provided herein. Furthermore, when elements of an embodiment are described in the form of "at least one of A and B," it should be understood that embodiments including element A only, element B only, and elements A and B are each contemplated. Furthermore, while some embodiments may realize other potential solutions and / or advantages over the prior art, whether or not a particular advantage is realized by a given embodiment does not limit the disclosure. Accordingly, the embodiments, features, and advantages disclosed herein are merely exemplary and should not be considered elements of or limit the scope of the appended claim(s) unless expressly recited in the claim(s). Similarly, references to "the present invention" should not be construed as generalizing all inventive subject matter disclosed herein, and should not be considered an element of or limiting the scope of any accompanying claim(s) unless expressly recited in the claim(s).

[0029]

[0031] 1 illustrates an exemplary quantum system 100 according to one or more embodiments. Features illustrated in quantum system 100 may be used in conjunction with other embodiments described herein. For example, remote entanglement operations (described in more detail below) may be implemented using one or more quantum systems 100.

[0030]

[0032] Quantum system 100 comprises multiple quantum components 125-1, 125-2, ..., 125-N, quantum component interconnect 145, control processor plane 105, and host processor 155. As used herein, multiple quantum components 125-1, 125-2, ..., 125-N refer to any suitable number of units that are physically and / or logically distinct from one another, e.g., multiple quantum chips. Quantum system 100 of FIG. 1 generally represents a large-scale quantum system, although other architectures of quantum system 100 are also contemplated, e.g., quantum system 100 having only a single "component."

[0031]

[0033] Each of the multiple quantum components 125-1, 125-2, ..., 125-N comprises a respective quantum data plane 140 and control and measurement plane 135 and is communicatively coupled to the control processor plane 105. The multiple quantum components 125-1, 125-2, ..., 125-N are communicatively coupled to one another by quantum component interconnects 145. In some aspects, the quantum data plane 140 comprises hardware that physically forms one or more qubits, as well as structures used to support and / or maintain one or more qubits. In some aspects, the quantum data plane 140 forms one or more AC dipoles. The qubits may have any suitable form, such as quantum dots, superconducting circuits, etc. In other aspects, the quantum data plane 140 comprises a quantized quantum device operable as a sensor. In still other aspects, the quantum data plane 140 comprises a repeater (or quantum information amplifier) ​​used in a quantum network. Thus, multiple implementations of entanglement circuit 205 of FIG. 2 described below can be used within quantum processing environments as well as outside of quantum processing environments.

[0032]

[0034] In some aspects, quantum data plane 140 comprises additional circuitry that operates to measure the state of one or more qubits and to manipulate the state of one or more qubits when performing operations. For example, gate operations may be performed using control signals that change the Hamiltonian (i.e., state description) of one or more qubits. In some aspects, quantum information in one or more qubits can be stored, changed, and / or read by transmitting microwave photons to one or more qubits.

[0033]

[0035] Control and measurement plane 135 comprises hardware that receives digital control signals from control processor plane 105 and converts the digital control signals into analog (or wave) control signals. The analog control signals are read and executed in quantum data plane 140 to perform quantum operations on one or more qubits. In some aspects, control and measurement plane 135 comprises one or more waveguides that support the transmission (and in some cases shielding) of signals to and from quantum data plane 140. For example, in quantum data plane 140 with qubits formed in superconducting circuits, control signals may be transmitted to the qubits through microwave waveguides that extend through a dilution refrigerator or other cooling device.

[0034]

[0036] Control and measurement plane 135 receives analog outputs (representing measurements of qubits) from quantum data plane 140 and converts the analog outputs to digital signals that are transmitted to control processor plane 105. Hardware included within control and measurement plane 135 may include additional shielding to mitigate the effects of environmental noise on the analog outputs received from quantum data plane 140.

[0035]

[0037] The control processor plane 105 implements a quantum algorithm or sequence of quantum operations and provides corresponding instructions that are implemented in the control and measurement plane 135. A host processor 155 is communicatively coupled to the control processor plane 105 and provides digital signal(s) that implement and / or interact with the quantum algorithm in the control processor plane 105.

[0036]

[0038] In some aspects, quantum algorithms are implemented using quantum circuits. Each quantum circuit represents a computing routine having a sequence of quantum operations on qubits in quantum data plane 140. In some aspects, quantum algorithms may be implemented using development tools and libraries. In some aspects, quantum algorithms include a sequence of gate operations and measurements performed in control and measurement plane 135.

[0037]

[0039] As shown, the control processor plane 105 is implemented as one or more processors 110 and memory 115. The one or more processors 110 are any electronic circuitry, including, but not limited to, one or a combination of a microprocessor, a microcontroller, an application specific integrated circuit (ASIC), an application specific instruction set processor (ASIP), and / or a state machine, that is communicatively coupled to the memory 115 and controls the operation of the control processor plane 105.

[0038]

[0040] The one or more processors 110 may include other hardware that runs software to control and process information. The one or more processors 110 execute software stored in memory 115 to perform any of the functions described herein. The one or more processors 110 control the operation and management of the computing device 105 by processing information (e.g., information received from input devices and / or communicatively coupled electronic devices).

[0039]

[0041] Memory 115 may store, either permanently or temporarily, data, operable software, or other information for one or more processors 110. Memory 115 may include any one or combination of volatile or non-volatile local or remote devices suitable for storing information. For example, memory 115 may include random access memory (RAM), read-only memory (ROM), magnetic storage device, optical storage device, or any other suitable information storage device, or combination of these devices. Software represents any suitable set of instructions, logic, or code embodied in a computer-readable storage medium, such as memory 115. In certain embodiments, software may include applications executable by one or more processors 110 to perform one or more of the functions described herein.

[0040]

[0042] In some aspects, some or all of the components of quantum system 100 operate within a cryogenic environment 150. As shown, the hardware of control processor plane 105, multiple quantum components 125-1, 125-2, ..., 125-N, and quantum component interconnect 145 are located within cryogenic environment 150, and one or more host processors 155 are located outside of cryogenic environment 150. In some aspects, one or more host processors 155 are considered "classical" processors, which include any electronic circuitry, including, but not limited to, a microprocessor, a microcontroller, an application specific integrated circuit (ASIC), an application specific instruction set processor (ASIP), and / or a state machine.

[0041]

[0043] In some aspects, a cryogenic cooling system using a liquefied gas, such as liquid nitrogen, liquid hydrogen, or liquid helium, may be in fluid communication with the cryogenic environment 150 to maintain a temperature of approximately 120 K (-153°C) or below. In some aspects, the cryogenic environment 150 has a temperature very close to absolute zero (0 K, -273.15°C) because superconductivity and its associated quantum properties are most pronounced at these temperatures. However, the cryogenic environment 150 may have any alternative suitable temperature (e.g., based on the critical temperature of the semiconductor material(s)) to ensure superconductivity.

[0042]

[0044] 2 illustrates a system 200 having an exemplary entanglement circuit 205 according to one or more embodiments. The entanglement circuit 205 may alternatively be described as a superinductor-based resonator. The system 200 may be used in conjunction with other embodiments described herein. For example, various components of the system 200 may be implemented within one or more quantum components 125-1, 125-2, ..., 125-N of the quantum system 100.

[0043]

[0045] The system includes an entanglement circuit 205 coupled to a first quantum system 260-1 and a second quantum system 260-2. The quantum systems 260-1, 260-2 include respective AC dipoles 255-1, 255-2. Each AC dipole 255-1, 255-2 may be implemented using any suitable technology that provides an oscillating charge representing a quantum coherent state, such as a quantum dot or a superconducting circuit. For example, the oscillating charge may represent a quantum fluctuation associated with the steady state of the quantum circuit. In some aspects, the AC dipoles 255-1, 255-2 are included in the same quantum data plane 140 of a particular quantum component 125-1, 125-2, ..., 125-N. In other embodiments, the AC dipoles 255-1, 255-2 are included in the quantum data plane 140 of different quantum components 125-1, 125-2, . . . , 125-N of the quantum system 100.

[0044]

[0046] Thus, in some aspects, quantum systems 260-1, 260-2 may represent one or more instances of quantum system 100. However, entanglement circuit 205 enables coherent quantum information transfer between AC dipoles 255-1, 255-2 regardless of their implementation. As described above, some exemplary implementations of AC dipoles 255-1, 255-2 include a set of one or more qubits, quantized quantum devices operable as sensors, and repeaters (or quantum information amplifiers) used in quantum networks. For example, when implemented within a quantum network repeater, AC dipoles 255-1, 255-2 may represent N-level quantum states of quantum systems 260-1, 260-2 and support quantum information swapping and entanglement between chips or other circuits.

[0045]

[0047] The entanglement circuit 205 includes a first port 215-1 coupled to a first quantum system 260-1 and a second port 215-2 coupled to a second quantum system 260-2. As shown, a node of the AC dipole 255-1 is coupled to a first port of a first mutual inductor 250-1 via respective capacitors 265-1, 265-2. The first mutual inductor 250-1 and capacitors 265-1, 265-2 may have any suitable implementation. The second port of the first mutual inductor 250-1 is coupled to the first port 215-1 of the entanglement circuit 205. Each of the first and second ports of the first mutual inductor 250-1 can operate as an input port or an output port, depending on the configuration of the system 200.

[0046]

[0048] A node of the AC dipole 255-2 is coupled to a first port of the second mutual inductor 250-2 via respective capacitors 265-3, 265-4. The second mutual inductor 250-2 and capacitors 265-3, 265-4 may have any suitable implementation. The second port of the second mutual inductor 250-2 is coupled to the second port 215-2 of the entanglement circuit 205. Each of the first and second ports of the second mutual inductor 250-2 can operate as an input port or an output port, depending on the configuration of the system 200.

[0047]

[0049] The entanglement circuit 205 further comprises a tunable super inductor 210 disposed between the first port 215-1 and the second port 215-2. In some aspects, the tunable super inductor 210 comprises a first branch 220-1 coupling the first mutual inductor 250-1 to the second mutual inductor 250-2 (i.e., coupling a first pair of nodes) and a second branch 220-2 coupling the first mutual inductor 250-1 to the second mutual inductor 250-2 (i.e., coupling a second pair of nodes). The first branch 220-1 comprises one or more Josephson junctions (JJs) 225-1, ..., 225-4 coupled in series with each other. Although four (4) JJs 225-1, ..., 225-4 are illustrated, other numbers of JJs in the first branch 220-1 are also contemplated.

[0048]

[0050] In some aspects, the second branch 220-2 comprises a superconducting quantum interference device (SQUID) 235 and a DC current source 245. The DC current source 245 enables tuning of the tunable super inductor 210 by controlling the amount of bias current provided by the DC current source 245. In other words, controlling the amount of bias voltage allows the SQUID 235 to modulate the loop inductance of the tunable super inductor 210. In some aspects, as described below, the electronic device 270 comprises an entanglement manipulation service 285 that provides a control signal used to select the bias current of the DC current source 245. Controlling the amount of bias current provided to the SQUID 235 allows the effective mode of the tunable super inductor 210 to be controlled. For example, the tunable super inductor 210 can be operated in a ring mode for a first value of the bias current and in a linear mode for a second value of the bias current (e.g., zero DC current). The DC current source 245 can have any suitable implementation, such as a MOSFET constant current source.

[0049]

[0051] In some embodiments, the second branch 220-2 (specifically, the SQUID 235) further comprises a third mutual inductor 240 having an input port coupled to a DC current source 245. The SQUID 235 comprises a first JJ 230-2 coupled in parallel with a series combination of a second JJ 230-3 and an output port of the third mutual inductor 240. The second branch 220-2 further comprises one or more JJs 230-1, 230-4 coupled in series with the SQUID 235. While four (four) JJs 230-1, ..., 230-4 are illustrated, other numbers of JJs within the second branch 220-2 are also contemplated. Furthermore, in some embodiments, the number of JJs included in the first branch 220-1 may differ from the number of JJs included in the second branch 220-2. Thus, in some aspects, the tunable superinductor 210 is formed as a superinductor loop comprising JJs 225-1, ..., 225-4 of the first branch 220-1, portions of the mutual inductors 250-1, 250-2, and JJs 230-1, 230-4 and SQUID 235 of the second branch 220-2.

[0050]

[0052] Each of JJs 225-1, ..., 225-4, 230-1, ..., 230-4 comprises a first superconducting section spaced from a second superconducting section by a weak link section. The first and second superconducting sections may be formed of any suitable superconducting material(s). In some embodiments, the weak link section comprises one of an insulating material, a non-superconducting metallic material, and a physical constriction providing an area of ​​reduced superconductivity. The weak link section has dimensions suitable for supporting quantum tunneling of electrons therethrough. Typically, the thickness of the weak link section may be on the order of tens of angstroms (Å) or on the order of a few microns, depending on the composition of the weak link section.

[0051]

[0053] The first and second superconductor sections, when cryogenically cooled in the cryogenic environment 150, are capable of passing electrons without offering any electrical resistance. The flow of supercurrent conducted across the weak link section and through the JJ is dominated by quantum tunneling of Cooper pairs (i.e., pairs of electrons with opposite spins bound together at cryogenic temperatures).

[0052]

[0054] In some embodiments, JJs 225-1, ..., 225-4, 230-1, ..., 230-4 may be implemented with similar parameters (e.g., the same dimensions, critical current values, etc.). For example, when SQUIDs 235 are arranged in parallel, JJs 225-1, ..., 225-4, 230-1, ..., 230-4 should have critical current values ​​as close to each other as possible, since the current tunability of the SQUIDs 235 depends on this. In other cases where SQUIDs 235 are arranged in series, a trade-off between capacitance and desired spectral mode may be possible. In other embodiments, some or all of JJs 225-1, ..., 225-4, 230-1, ..., 230-4 may be implemented with different parameters.

[0053]

[0055] Collectively, the JJs 225-1, ..., 225-4, 230-1, ..., 230-4 of the tunable superinductor 210 effectively operate as classical inductors with large inductance (and large impedance), providing stronger coupling between the quantum systems 260-1, 260-2. Thus, the tunable superinductor 210 supports stronger entanglement between the AC dipoles 255-1, 255-2, because the large impedance provides greater coupling and mitigates induced noise during the entanglement operation. Furthermore, in some aspects, the various components of the system 205 can be coupled to each other using high-quality connections (e.g., superconducting wire segments). These high-quality connections improve the coupling and entanglement between the AC dipoles 255-1, 255-2. By integrating the SQUID 235 into the tunable super inductor 210, the inductance of the tunable super inductor 210 can be precisely adjusted, and the impedance and resonant frequency of the entanglement circuit 205 can be better controlled.

[0054]

[0056] System 200 further includes electronic device 270. As used herein, "electronic device" generally refers to any device having electronic circuitry. The electronic circuitry provides processing or computing capabilities and implements logic and / or executes program code to perform various operations that collectively define the functionality of the electronic device. The functionality of an electronic device includes, for example, the ability to communicate with one or more other electronic devices when connected to the same network. Electronic devices may be implemented in any suitable form factor, whether relatively static (e.g., mainframe, computer terminal, server, kiosk, workstation) or mobile (e.g., laptop computer, tablet, handheld, smartphone, wearable device). Communication capabilities between electronic devices may be achieved using any suitable technique, such as conductive cables, wireless transmission, optical transmission, etc. In some embodiments, electronic device 270 may be implemented outside of cryogenic environment 150. In other embodiments, electronic device 270 may be implemented partially or completely within cryogenic environment 150.

[0055]

[0057] Computing device 270 includes one or more processors 275 and memory 280. The one or more processors 275 are any electronic circuitry including, but not limited to, one or a combination of a microprocessor, a microcontroller, an application specific integrated circuit (ASIC), an application specific instruction set processor (ASIP), and / or a state machine. The optional electronic circuitry is communicatively coupled to memory 280 and controls the operation of electronic device 270. The one or more processors 275 are not limited to a single processing device, but may include multiple processing devices.

[0056]

[0058] The one or more processors 275 may include other hardware that runs software to control and process information. In some aspects, the one or more processors 275 execute software stored in memory 280 to perform any of the functions described herein. The one or more processors 275 control the operation and management of the computing device 270 by processing information (e.g., information received from input devices and / or communicatively coupled electronic devices).

[0057]

[0059] Memory 280 may store data, operable software, or other information for one or more processors 275, either permanently or temporarily. Memory 280 may include any one or combination of volatile or non-volatile local or remote devices suitable for storing information. For example, memory 280 may include random access memory (RAM), read-only memory (ROM), magnetic storage devices, optical storage devices, or any other suitable information storage device, or a combination of these devices. Software represents any suitable set of instructions, logic, or code embodied in a computer-readable storage medium. For example, software may be embodied in memory 280, a disk, a CD, or a flash drive. In certain embodiments, software may include applications executable by one or more processors 275 to perform one or more of the functions described herein.

[0058]

[0060] In this embodiment, memory 280 stores entanglement manipulation service 285 that controls remote entanglement of AC dipoles. In some aspects, entanglement manipulation service 285 enables and / or disables remote entanglement manipulation within system 200 and / or controls one or more parameters that define remote entanglement manipulation. As shown, entanglement manipulation service 285 is coupled to AC dipoles 255-1, 255-2 (or to quantum systems 260-1, 260-2) and to SQUID 235 (or to tunable superinductor 210). In some aspects, entanglement manipulation service 285 provides signals that control the operation of quantum devices 260-1, 260-2 to interact with entanglement circuit 205. In some aspects, the signal causes quantum devices 260-1, 260-2 to adiabatically change their quantum states to maximize the charge dipole (or AC charge dipole) of each of AC dipoles 255-1, 255-2, i.e., the left plates of capacitors 265-1, 265-2 and the right plates of capacitors 265-3, 265-4. In some aspects, remote entanglement manipulation service 285 may further provide signals to control the operation of SQUID 235, for example, by selecting or adjusting the bias current of DC current source 245.

[0059]

[0061] In some aspects, the inductance of the tunable super inductor 210 is controlled so that the quantum systems 260-1, 260-2 can be operated and developed independently of one another. When remote entanglement operation of the system 200 is desired, the quantum systems 260-1, 260-2 are controlled (e.g., by signals from the entanglement operation service 285) to perform precisely timed (or synchronized) operation. The tunable super inductor 210 typically operates for the entire duration of the remote entanglement operation. During remote entanglement operation, one of the AC dipoles 255-1, 255-2 generates a current that is inductively coupled into the tunable super inductor 210. The induced current in the tunable super inductor 210 is then inductively coupled into the other of the AC dipoles 255-1, 255-2 to achieve remote entanglement.

[0060]

[0062] The inductance presented by the tunable super inductor 210 can be further fine-tuned to maximize entanglement manipulation. Fine-tuning operations tend to relax shape and size constraints, allowing the system 200 to be more tolerant of any manufacturing imperfections. For example, an AC line can be added to the SQUID 235 to support finer tuning of the tunable super inductor 210. Such an implementation may also allow for turning off (or disabling) the tunable super inductor 210, since the inductance presented by the tunable super inductor 210 can be controlled to minimize or eliminate coupling between the AC dipoles 255-1, 255-2.

[0061]

[0063] The entanglement circuit 205 with the tunable super inductor 210 offers several advantages over conventional stripline resonator designs. First, the entanglement circuit 205 suppresses charge fluctuations and supports a larger quality factor. The tunable super inductor 210 reduces the resistance quantum This allows for a larger impedance to be achieved than with a stripline resonator, while presenting a lower capacitance than a stripline resonator, which improves manufacturing uniformity. Second, the entanglement circuit 205 improves dipole coupling and supports greater coupling between the AC dipoles 255-1 and 255-2. This advantage is particularly useful for quantum remote sensing (e.g., using interferometer-based devices) that employs remote entanglement between a probe and a receiver. This enhances the ability to detect remote targets and transfer quantum information. Coupling is often expected to be proportional to the square root of the impedance. This is controlled by the selection of the critical currents of the JJs 225-1, ..., 225-4, 230-1, ..., 230-4, and can be fine-tuned using the SQUIDs 235.

[0062]

[0064] Another advantage provided by system 200 is that the superconducting components of system 200 can be fabricated from a different semiconductor fabrication process than the quantum device. In some aspects, entangled circuit 205 can be formed in a first process, a semiconductor chip can be formed in a second process, and entangled circuit 205 can be bonded to the semiconductor chip in the final quantum device.

[0063]

[0065] 3 illustrates an exemplary method 300 for remote entanglement of alternating current (AC) dipoles in accordance with one or more embodiments. Method 300 may be used in conjunction with other embodiments described herein. For example, although certain blocks are described as being performed using entanglement manipulation service 285, method 300 may be performed using various components of quantum system 100 and / or system 200 of FIG. 2.

[0064]

[0066] Method 300 begins at block 305, where entanglement operation service 285 determines whether remote entanglement operation is enabled within system 200. If remote entanglement operation is not enabled (“NO”), method 300 repeats block 305, e.g., after a periodic delay. If entanglement operation is enabled (“YES”), method 300 proceeds from block 305 to block 315, where a bias current is supplied to tunable super inductor 210 of system 200. In some aspects, the bias current is supplied to SQUID 235 included in branch 220-2 of tunable super inductor 210. By supplying the bias current, entanglement circuit 205 is operated during remote entanglement operation. In some aspects, block 315 is performed before block 305. Thereby, the entanglement circuit 205 operates in a desired configuration before controlling the AC dipoles (connected to the entanglement circuit 205) to achieve remote entanglement.

[0065]

[0067] From block 315, method 300 proceeds to block 325, where entanglement manipulation service 285 provides control signals to first AC dipole 255-1 and / or second AC dipole 255-2 to maximize their charge dipole(s). In some aspects, the signals cause changes to quantum states to maximize the charge dipole of first AC dipole 255-1 and / or second AC dipole 255-2. In optional block 335, entanglement manipulation service 285 provides control signals to adjust bias currents.

[0066]

[0068] The method 300 proceeds from block 325 or optional block 335 to block 345, where a current is inductively coupled from the first AC dipole 255-1 into the tunable super inductor 210. Inductively coupling a current induces a current in the tunable super inductor 210. The method 300 then proceeds from block 345 to block 355, where an induced current is inductively coupled from the tunable super inductor into the second AC dipole 255-2. The method 300 ends after completing block 355.

[0067]

[0069] As will be appreciated by one of ordinary skill in the art, aspects described herein may be embodied as a system, method, and / or computer program product. Accordingly, aspects may take the form of entirely hardware aspects, entirely software aspects (including firmware, resident software, microcode, etc.), or aspects combining software and hardware aspects, all of which may be broadly referred to herein as "circuits," "modules," or "systems." Furthermore, aspects described herein may take the form of a computer program product embodied in one or more computer-readable storage medium(s) having computer-readable program code embodied therein.

[0068]

[0070] The program code embodied in the computer readable storage medium may be transmitted using any suitable medium, including but not limited to wireless, wired, fiber optic cable, RF, etc., or any suitable combination thereof.

[0069]

[0071] Computer program code for carrying out operations of aspects of the present disclosure may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" programming language or similar programming languages. The program code may run entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet Service Provider).

[0070]

[0072] Aspects of the present disclosure are described herein with reference to flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to aspects of the present disclosure. It will be understood that each block of the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose or special-purpose computer or other programmable data processing device to produce a machine. These instructions, executed via the processor of the computer or other programmable data processing device, thereby create means for performing the function(s) / acts identified in the block(s) of the flowcharts and / or block diagrams.

[0071]

[0073] These computer program instructions may also be stored on a computer-readable medium that may direct a computer, other programmable data processing apparatus, or other device to function in a particular manner. The instructions stored in the computer-readable medium thereby produce an article of manufacture. The instructions include instructions that implement the functions / acts identified in the flowchart and / or block diagram block(s).

[0072]

[0074] Computer program instructions may also be loaded into a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be executed on the computer, other programmable data processing apparatus, or other device to generate a computer-implemented process, whereby the instructions executing on the computer, other programmable data processing apparatus, or other device provide a process for implementing the function(s) / act(s) identified in the flowchart and / or block diagram block(s).

[0073]

[0075] The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various aspects of the present disclosure. As such, each block in the flowcharts and block diagrams may represent a module, segment, or portion of code, including one or more executable instructions for implementing specific logical function(s). In some alternative implementations, the functions shown in the blocks need not occur in the order depicted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially simultaneously, or the blocks may be executed in reverse or out of order, depending on the functionality involved. It should also be noted that each block of the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a special-purpose hardware-based system that performs particular functions or functions, or by a combination of special-purpose hardware and computer instructions.

[0074]

[0076] While the foregoing is directed to aspects of the disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, the scope of which is defined by the following claims.

Claims

1. A method (300) for remote entanglement of alternating current (AC) dipoles, comprising: Providing (315) a bias current to the adjustable super inductor (210); inductively coupling (345) current from a first AC dipole (255-1, 255-2) into the tunable super inductor; and and inductively coupling (355) an induced current from the tunable super inductor into a second AC dipole (255-2, 255-1).

2. 2. The method of claim 1, further comprising providing (325) a control signal to one or both of the first AC dipole and the second AC dipole to maximize a charge dipole between the first AC dipole and the second AC dipole.

3. The tunable super inductor comprises: Superconducting quantum interference devices (SQUIDs) (235), and The method of claim 1 , comprising a direct current (DC) current source (245) for providing the bias current.

4. a first mutual inductor (250-1, 250-2) coupling the first AC dipole to a first port (215-1, 215-2) of the tunable super inductor; The method of claim 3, wherein a second mutual inductor (250-2, 250-1) couples the second AC dipole to a second port (215-2, 215-1) of the tunable super inductor.

5. The tunable super inductor comprises: a first branch (220-1) coupling the first mutual inductor to the second mutual inductor, the first branch (220-1) comprising one or more Josephson junctions (JJs) (225-1, ..., 225-4) coupled in series; and 5. The method of claim 4, further comprising a second branch (220-2) coupling the first mutual inductor to the second mutual inductor, the second branch (220-2) comprising the SQUID and the DC current source.

6. the second branch further comprises a third mutual inductor (240) having an input port coupled to the DC current source; 6. The method of claim 5, wherein the SQUID comprises a first JJ (230-2) coupled in parallel with a series combination of a second JJ (230-3) and an output port of the third mutual inductor.

7. The method of claim 6 , wherein the second branch further comprises one or more JJs (230-1, 230-4) coupled in series with the SQUID.

8. a first alternating current (AC) dipole (255-1, 255-2); a second AC charge dipole (255-2, 255-1), and The system comprises an entanglement circuit (205) coupled to the first AC charge dipole and the second AC charge dipole, the entanglement circuit (205) comprising a tunable super inductor (210).

9. The tunable super inductor comprises: Superconducting quantum interference devices (SQUIDs) (235), and The system of claim 8, comprising a direct current (DC) current source (245).

10. a first mutual inductor (250-1, 250-2) coupled to the first AC charge dipole and a first port (215-1, 215-2) of the entanglement circuit; and 10. The system of claim 9, further comprising a second mutual inductor (250-2, 250-1) coupled to the second AC charge dipole and a second port (215-2, 215-1) of the entanglement circuit.

11. The tunable super inductor comprises: a first branch (220-1) coupling the first mutual inductor to the second mutual inductor, the first branch (220-1) comprising one or more Josephson junctions (JJs) (225-1, ..., 225-4) coupled in series; and 11. The system of claim 10, further comprising a second branch (220-2) coupling the first mutual inductor to the second mutual inductor, the second branch (220-2) comprising the SQUID and the DC current source.

12. the second branch further comprises a third mutual inductor (240) having an input port coupled to the DC current source; 12. The system of claim 11, wherein the SQUID comprises a first JJ (230-2) coupled in parallel with a series combination of a second JJ (230-3) and an output port of the third mutual inductor.

13. The system of claim 12 , wherein the second branch further comprises one or more JJs (230-1, 230-4) coupled in series with the SQUID.

14. 13. The system of claim 12, wherein the DC current source is configured to supply a bias current to the input port, the value of the bias current being selected to maximize coupling between the first AC charge dipole and the second AC charge dipole.

15. a first port (215-1, 215-2) coupled to a first alternating current (AC) dipole (255-1, 255-2); a second port (215-2, 215-1) coupled to a second AC dipole (255-2, 255-1); and The apparatus comprises a tunable super inductor (210) coupled to the first port and the second port.

16. The tunable super inductor comprises: Superconducting quantum interference devices (SQUIDs) (235), and 16. The apparatus of claim 15, comprising a direct current (DC) current source (245).

17. a first mutual inductor (250-1, 250-2) coupled to the first AC charge dipole and the first port; and 17. The apparatus of claim 16, further comprising a second mutual inductor (250-2, 250-1) coupled to the second AC charge dipole and the second port.

18. The tunable super inductor comprises: a first branch (220-1) coupling the first mutual inductor to the second mutual inductor, the first branch (220-1) comprising one or more Josephson junctions (JJs) (225-1, ..., 225-4) coupled in series; and 18. The apparatus of claim 17, further comprising a second branch (220-2) that couples the first mutual inductor to the second mutual inductor, the second branch (220-2) comprising the SQUID and the DC current source.

19. the second branch further comprises a third mutual inductor (240) having an input port coupled to the DC current source; 20. The apparatus of claim 18, wherein the SQUID comprises a first JJ (230-2) coupled in parallel with a series combination of a second JJ (230-3) and an output port of the third mutual inductor.

20. 20. The apparatus of claim 19, wherein the second branch further comprises one or more JJs (230-1, 230-4) coupled in series with the SQUID.

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