Charged Particle Trap Operation

Abstract

A method of operating a charged particle trap (3) including a set of trap electrodes (121, 122, 12 N ). The method includes trapping a first charged particle (11) providing a first qubit (21) having a first transition frequency (f1) at a first position (41), and trapping a second charged particle (12) providing a second qubit (21) having a second transition frequency at a second position (42). The method includes applying a potential gradient (11) to the first and second charged particles, the first and second charged particles respectively receiving magnitudes (g1, g2) of the first and second potential gradients, the potential gradient oscillating at a given frequency (f G ) and being monochromatic. The method includes applying a first oscillating potential to a first electrode (121) at a first given frequency (f E1 ) so as to apply a first oscillating electric field (141) to the first charged particle, and applying a second oscillating potential to a second electrode (122) at a second frequency (f E2 ) so as to apply a second oscillating electric field to the second charged particle.

Description

Technical Field

[0001] The present invention relates to operating a charged particle trap.

Background Art

[0002] Quantum computing architectures require the ability to control individual qubits. Typically, this is achieved using a spatially varying control field, whereby each qubit receives a different locally adjustable coupling.

[0003] In trapped ion architectures, two approaches are mainly used: a focused laser beam and a spatially varying magnetic field. However, it is difficult to generate highly controlled and localized lasers or magnetic fields on a large scale. As a result, common approaches used to process single qubit operations are to use an incompletely localized field and to manipulate the ions, i.e., to move the ions in and out of the region where the field is applied. In this so-called "shuttling-based" approach, single qubit operations consist of ion shuttling and applying laser or magnetic field pulses.

[0004] These approaches can have one or more drawbacks. For example, ion shuttling is slow due to the need to filter control electrodes, which is a bottleneck for performing single qubit operations. Furthermore, simply shuttling ions into the field generated by a single source of origin does not allow for individual phase control. Therefore, in order to operate N qubits efficiently in parallel, O(N) individual adjustable laser or magnetic field sources of origin are typically required. Incorporating these sources of origin into an ion trap system is difficult and resource-intensive.

[0005] R. T. Sutherland, R. Srinivas, and D. T. C. Allcock, "Individual addressing of trapped ion qubits with geometric phase gates", (June 14, 2022), available from https: / / arxiv.org / pdf / 2206.06546.pdf, describes a concept for the individual processing of ion qubits that selects trapped ion qubits via their motional frequencies. In this concept, one ion acts as the "target" qubit and the other ions act as "spectator" qubits. Both qubits are driven by a pair of a two-color microwave field and an rf B field gradient, resulting in a potential gradient that is three-color.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Non-Patent Documents

[0007]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Means for Solving the Problems

[0008] According to a first aspect of the present invention, there is provided a method of operating a charged particle trap including a set of trap electrodes. The method includes trapping a first charged particle having a first transition frequency at a first position, and trapping a second charged particle having a second transition frequency at a second position.

[0009] The method includes applying a potential gradient to the first charged particle and the second charged particle, wherein the first charged particle receives a magnitude of the first potential gradient, the second charged particle receives a magnitude of the second potential gradient, and the potential gradient oscillates at a given frequency and is substantially monochromatic. The method includes applying a first oscillating potential to a first electrode at a first frequency so as to apply a first oscillating electric field to the first charged particle, and applying a second oscillating potential to a second electrode at a second frequency so as to apply a second oscillating electric field to the second charged particle, while applying the potential gradient.

[0010] The first oscillating electric field is preferably applied locally to the first charged particle, and the second oscillating electric field is preferably applied locally to the second charged particle.

[0011] The first transition frequency and the second transition frequency may be different. The first frequency and the second frequency (of the oscillating potential) may be different.

[0012] The potential gradient may be applied over a longer period than the first and second oscillating potentials, or the first and second oscillating potentials may be applied over a longer period than the potential gradient.

[0013] The first oscillating electric field can have a first phase value, and the second oscillating electric field can have a second different phase value. The phase of the quantum gate (i.e., the rotation axis in the Bloch state) can be adjusted by changing the phase of the oscillating electric field relative to the phase of the potential gradient.

[0014] The step of applying a potential gradient may include applying at least one magnetic field gradient and / or a laser field to the first and second charged particles.

[0015] The method may further include applying carrier drive to the first charged particle and the second charged particle.

[0016] The step of applying a potential gradient to the first charged particle and the second charged particle may include driving an oscillating current through an elongated conductive element to generate at least one magnetic field.

[0017] The elongated conductive element may include a first region and a second region, and the first region and the second region of the elongated conductive element are not collinear. The elongated conductive element may include driving a first oscillating current through a first elongated conductive element and driving a second oscillating current through a second elongated conductive element spaced apart from the first elongated conductive element.

[0018] The charged particle trap may include a substrate having a main surface.

[0019] At least a first set of the set of trap electrodes, or all of the trap electrodes, may be disposed on the main surface or another surface of the substrate. A second set of the set of trap electrodes can be supported on a different surface and is not in the same plane as the first set. The charged particle trap may include at least one elongated conductive element disposed on the main surface or another surface of the substrate to generate at least one magnetic field.

[0020] At least one elongated conductive element may be disposed on the main surface of the substrate. At least one elongated conductive element may be disposed on another surface of the substrate. At least one elongated conductive element may be disposed on different substrates.

[0021] The set of trap electrodes can include a first array and a second array of trap electrodes, and at least one elongated conductive element can be interposed between the first array of trap electrodes and the second array.

[0022] The first array of trap electrodes may comprise first trap electrodes spaced along a first direction, and the second array of trap electrodes may comprise second trap electrodes spaced along the first direction, and the first array of trap electrodes and the second array of trap electrodes are preferably spaced in a second direction orthogonal to the first direction.

[0023] One elongated conductive element can be supported on different surfaces and can be assumed to be not on the same plane as the first set of trap electrodes.

[0024] The step of applying a potential gradient to the first charged particles and the second charged particles may include the step of illuminating the first charged particles and the second charged particles with at least one laser beam.

[0025] The first charged particles can have a given oscillation mode with a given oscillation direction, and the method includes applying a potential gradient such that the potential gradient in the first charged particles has a component not perpendicular to the given oscillation direction, and the potential gradient in the second charged particles has a component not perpendicular to the given oscillation direction, and applying a first oscillating electric field such that the first oscillating electric field is not perpendicular to the given oscillation direction, and applying a second oscillating electric field such that the second oscillating electric field is not perpendicular to the given oscillation direction.

[0026] The set of trap electrodes can include a first electrode and a second electrode. In other words, the trap electrodes can be used to provide a local oscillating electric field.

[0027] The method may include trapping a third charged particle that provides a third qubit having a third transition frequency at a third position, and applying a potential gradient to the third charged particle, wherein the third charged particle is subject to the magnitude of the third potential gradient. The method may include applying a third oscillating potential to a third electrode at a third frequency so as to apply a third oscillating electric field to the third charged particle while the potential gradient is being applied.

[0028] The method may include trapping N charged particles, each charged particle being trapped at a respective position, and each charged particle providing a respective qubit having a respective transition frequency. The method may include applying a potential gradient to the N charged particles, the charged particles being subject to the magnitude of the respective potential gradients. The method may include applying a respective oscillating potential to a respective electrode at a respective frequency so as to apply a respective oscillating electric field to each charged particle while the potential gradient is being applied.

[0029] There may be between 10 and 1000 charged particles.

[0030] The charged particle may be an ion, an atom, or a molecule such as a calcium ion with a net charge, an electron, or a positron. The charged particles may include different charged particles such as different ions.

[0031] According to a second aspect of the present invention, there is provided a system comprising a charged particle trap including a set of trap electrodes and a control system for controlling the charged particle trap. The control system is configured to trap a first charged particle having a first transition frequency at a first position, trap a second charged particle having a second transition frequency at a second position, and apply a potential gradient to the first charged particle and the second charged particle, wherein the first charged particle receives the magnitude of the first potential gradient, the second charged particle receives the magnitude of the second potential gradient, and the potential gradient oscillates at a given frequency. The control system is configured to apply a first oscillating potential to a first electrode at a first frequency so as to apply a first oscillating electric field to the first charged particle, and apply a second oscillating potential to a second electrode at a second frequency so as to apply a second oscillating electric field to the second charged particle while applying the potential gradient.

[0032] Here, specific embodiments of the present invention will be described by way of example with reference to the accompanying drawings.

Brief Description of the Drawings

[0033]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0034] Introduction In the following, a method for implementing parallel single qubit control that does not require the use of individually adjustable laser or magnetic field sources is described. The method does not require a localized laser or magnetic field, or for ions to be moved in and out of a localized region of processing (i.e., the region where the localized laser or magnetic field is applied), thereby improving the problem of the speed bottleneck associated with ion shuttling. Instead, an overall potential gradient (e.g., generated using one or more electric currents flowing through one or more elongated conductors such as wires or tracks) can be used in combination with a localized oscillating electric field, preferably at a low frequency (e.g., 0.1 - 20 MHz). Such an electric field is easier to localize and apply compared to a laser or magnetic field. Further, local control can be achieved using an existing trap structure (e.g., an ion trap electrode with surface electrodes) rather than providing an additional dedicated laser or magnetic field source. The method is parallelizable, and local control can be achieved by adjusting the amplitude and phase of the local electric field. In other words, the rotation phase of a single qubit can be controlled via a locally adjustable electric field phase.

[0035] Referring to FIG. 1, a plurality of charged particles 11, 12, …, 1 N are shown.

[0036] In this case, the charged particles 11, 12, …, 1 Nis an ion. However, the charged particle may take the form of an atom or molecule with a net charge, an electron, or a positron. There may be three or more charged particles 11, 12, …, 1 N For example, there may be between 10 and 1000 charged particles 11, 12, …, 1 N i.e., 10 ≦ N ≦ 1000. There may be more than 1000 charged particles.

[0037] Each ion 11, 12, …, 1 N provides respective quantum bits 21, 22, …, 2 N and is spatially confined in an ion trap 3 at respective positions 41, 42, …, 4 N Each quantum bit 21, 22, …, 2 N has two states 5, 6 and a transition 7 between the two states 5, 6. Each quantum bit 21, 22, …, 2 N has respective transition frequencies f1, f2, …, f N

[0038] Referring also to FIG. 2, the individual quantum bits 21, 22, …, 2 N can be individually controlled using a system 8.

[0039] The system 8 includes a potential gradient generator 9 for generating a potential gradient 11. The potential gradient generator 9 can take the form of one or more magnetic field gradient sources and / or laser field sources that generate an oscillating magnetic field gradient or laser field 11 having a frequency f N that can be applied globally to the ions 11, 12, …, 1 G One or more generators 9 can be used to generate the potential gradient 11 although the number of generators 9 is less than the number of ions 11, 12, …, 1 N

[0040] Each ion 11, 12, …, 1 N has respective magnitudes g1, g2, …, g N ​​The potential gradient 11 can be in any direction.

[0041] Ions 11, 12, …, 1 N are subjected to a monochromatic (or "single-toned") potential gradient 11. Thus, if a single potential gradient generator 9 is used, that potential gradient generator 9 is arranged to generate a monochromatic potential gradient 11, so that the ions 11, 12, ..., 1 N ions 11, 12, ..., 1 N The electrodes are arranged to generate a net potential gradient 11 which is monochromatic as encountered by the

[0042] A monochromatic gradient can have one or more benefits, such as making it easier to implement and helping to reduce resulting operational errors. For example, sending a single frequency allows for simple single-point impedance matching.

[0043] System 8 is a set of ions 11, 12, …, 1 N oscillating electric fields 141, 142, ..., 14 N A plurality of electrodes 121, 122, ..., 12 N and single source 131, 132, …, 13 N Electrodes 121, 122, ..., 12 N are ions 11, 12, …, 1 N may be the same as at least some of the electrodes used to trap the

[0044] Referring also to FIG. 3, in the method of single qubit operation, the trapped ion qubits 21, 22, ..., 2 N are trapped in the ion trap 3 (step S1).

[0045] The potential gradient generator 9 is iis switched over a period of time (step S2). Each of the ions 11, 12, …, 1 N is subject to respective potential gradients having magnitudes g1, g2, …, g N . The magnitude of the potential gradient 11 oscillates at the frequency f G . The potential gradient 11 is monochromatic.

[0046] At the same time, signal sources 131, 132, …, 13 N apply an oscillation signal to electrodes 121, 122, …, 12 N (step S3). Each of the ions 11, 12, …, 1 N is subject to respective electric fields 141, 142, …, 14 Ei having respective frequencies f i , amplitudes e i and phases k N (where i = 1, 2, …, N). These parameters are locally adjustable. By adjusting the phase k i , parallel operations can be locally implemented.

[0047] The potential gradient 11 and the electric fields 141, 142, …, 14 N are applied simultaneously over a period of time t i . At the end of this time period, one or more of the qubits 21, 22, …, 2 N may have received the processed operations.

[0048] Here, an example of a system using a globally applied potential gradient and locally applied electric fields is described.

[0049] System using a magnetic field gradient generated by a current Referring to FIG. 4, a first system 31 for quantum information processing using trapped charged particles 32 is shown.

[0050] System 31 includes a charged particle trap 33 that can be housed in a vacuum chamber (not shown) that provides an ultra-high vacuum environment for isolating individual charged particles, and a control system 34 for the trap 33.

[0051] In this case, the charged particles 32 are in the form of ions such as calcium ions ( 40 Ca + ). For the sake of brevity, the charged particles are also referred to here as "ions". However, the charged particles may take the form of atoms or molecules with a net charge, or charged elementary particles such as electrons or positrons.

[0052] As described above, each ion 32 provides a respective quantum bit 35 and can be spatially confined at its respective position 36 in the trap 33. Each quantum bit has two states 37, 38 and a transition 39 between the two states 37, 38. Each quantum bit 35 has a respective transition frequency f i which can be measured using, for example, Rabi or Ramsey spectroscopy.

[0053] The trap 33 takes the form of a surface electrode trap and includes a substrate 40 having an upper surface 41 that supports a plurality of electrodes 42, 43, 44.

[0054] The electrodes 42, 43, 44 include a central electrode 42 in the form of a strip extending along a longitudinal axis 45, and a first electrode 431 and a second electrode 432 in the form of strips extending on both sides along the central electrode 42 such that the central electrode 42 is interposed therebetween. An alternating signal at an RF frequency is applied to the first electrode 431 and the second electrode 432 (hereafter also referred to as "the first RF electrode and the second RF electrode") to generate a ponderomotive force that confines the potential.

[0055] The electrodes 42, 43, 44 include trap electrodes 44, 44 arranged in two linear arrays (or "pillars" or "columns") outside the first RF electrode 431 and the second RF electrode 432 1,1 、44 1,2, 44 1,3 , 44 1,4 , 44 1,5 , 44 1,6 , 44 2,1 , 44 2,2 , 44 2,3 , 44 2,4 , 44 2,5 , 44 2,6 comprises a set of

[0056] Examples of surface electrode traps can be found in WO2021 / 205145A1, which is incorporated herein by reference.

[0057] The control system 34 includes a current source 46 for driving an oscillating current I(t) through the center electrode 42 between the first end 47 and the second end 48. The second end 48 of the center electrode 42 is grounded. As will be described in more detail, the current source 46 and the center electrode 42 are used to generate a magnetic field 50 oscillating at a frequency f G at which ions are subjected to the respective magnitudes of the magnetic field gradient 51 (FIG. 5).

[0058] The control system 34 includes a first voltage source 521 and a second voltage source 522 for applying signals to the first RF electrode 431 and the second RF electrode 432, respectively, and a voltage source 53 for applying respective signals to the trap electrodes 44 1,1 , 44 1,2 , 44 1,3 , 44 1,4 , 44 1,5 , 44 1,6 , 44 2,1 , 44 2,2 , 44 2,3 , 44 2,4 , 44 2,5 , 44 2,6 , respectively. 1,1 , 53 1,2 , 53 1,3 , 53 1,4 , 53 1,5 , 53 1,6 , 53 2,1 , 53 2,2 , 53 2,3 , 53 2,4 , 532,5 , 53 2,6 comprises a source of origin 50, 521, 522, 53 1,1 , 53 1,2 , 53 1,3 , 53 1,4 , 53 1,5 , 53 1,6 , 53 2,1 , 53 2,2 , 53 2,3 , 53 2,4 , 53 2,5 , 53 2,6 is controlled by the computer system 54.

[0059] Referring also to FIG. 5, the operation of the system 31 will be described in more detail.

[0060] Two trapped ions 321, 322 can be processed in parallel in the surface electrode trap 33.

[0061] Both ions 321, 322 are connected to one potential gradient source, i.e., the central electrode 42. The potential gradient 51 is generated by passing an oscillating current I(t) through the central electrode 45. Local control is obtained by applying an oscillating voltage to the first electrode 44 1,1 and the second electrode 44 1,6 , etc. The ions 321, 322 are sufficiently separated from each other such that the connection from the first electrode 44 1,1 to ion 322 and the connection from the second electrode 44 1,6 to ion 321 are very small.

[0062] The trap electrode 44 can be used not only to apply a DC electric field used in the trap but also to apply an oscillating electric field. For example, the first source 53 1,1 results in a first DC offset voltage V A and a first oscillating voltage V(t)=V1·cos(2πf E1 +k1), and the first combined voltage can be applied to the first electrode 44 1,1 , and the second source 53 1,6is the second DC offset voltage V B and the second oscillating voltage V(t) = V2·cos(2πf E2 + k2), and the first combined voltage can be applied to the second electrode 44 1,6 .

[0063] Referring to FIG. 6, a suitable signal generation configuration 55 is shown.

[0064] The DC voltage source 56 can include a digital - to - analog converter 57 and an amplifier 58. The voltage source 56 is connected to the electrode 44 via a low - pass RC filter 59 having a node 60 between a resistor R and a capacitor C. The AC voltage source 61 can include an AC source 62, an amplifier 63, and an optional series filter 64 connected to the output of the source 61. The output of the source 61, or, if used, the output of the filter 64, is connected to the node 60 and thus to the electrode.

[0065] A system using the electric field gradient generated by a laser Referring to FIG. 7, a second system 71 for quantum information processing using trapped charged particles 72 is shown.

[0066] The system 71 includes a charged particle trap 73 that can be housed in a vacuum chamber (not shown) providing an ultra - high vacuum environment for isolating individual charged particles, and a control system 74 for the trap 73.

[0067] In this case, the charged particles 72 take the form of ions such as calcium ions ( 40 Ca + ). For simplicity, the charged particles are also referred to here as "ions". However, the charged particles may take the form of an atom or molecule with a net charge, or a charged elementary particle such as an electron or a positron.

[0068] As described above, each ion 72 provides a respective qubit 75 and can be spatially confined at respective positions 76 in trap 73. Each qubit has two states 77, 78 and a transition 79 between the two states 77, 78. Each qubit 75 has a respective transition frequency f i thereof.

[0069] Trap 73 takes the form of a microfabricated surface electrode trap and comprises a substrate 80 having an upper surface 81. Trap 73 comprises an elongate slot 82 passing through substrate 80. On either side of slot 82, the upper surface of substrate 80 supports electrode layer stacks 831, 832.

[0070] Each electrode stack layer 831, 832 comprises a set of lower electrodes 841, 842, 84 1,1 84 2,1 (the lowermost electrode is not visible in FIGS. 6 or 7), a set of dielectric layers 851, 852, and a set of upper electrodes 861, 862, 86 1,1 86 1,2 86 1,3 86 1,4 86 1,5 86 2,1 86 2,2 86 2,3 86 2,4 86 2,5 . Each dielectric layer 851, 852 is interposed between lower electrodes 841, 842 and upper electrodes 861, 862.

[0071] Control system 74 includes a laser 87 used to generate a beam 88 that generates an electric field gradient 89.

[0072] Control system 74 applies respective signals to lower electrodes 84, 84 1,1 84 1,2 84 1,3 84 1,4 84 1,5 84 2,1 84 2,2 84 2,3 84 2,4 84 2,5Voltage sources 90, 90 for applying to 1,1 , 90 1,2 , 90 1,3 , 90 1,4 , 90 1,5 , 90 2,1 , 90 2,2 , 90 2,3 , 90 2,4 , 90 2,5 and a first set of, and signals to upper electrodes 86, 86 1,1 , 86 1,2 , 86 1,3 , 86 1,4 , 86 1,5 , 86 2,1 , 86 2,2 , 86 2,3 , 86 2,4 , 86 2,5 voltage sources 91, 91 for applying to 1,1 , 91 1,2 , 91 1,3 , 91 1,4 , 91 1,5 , 91 2,1 , 91 2,2 , 91 2,3 , 91 2,4 , 91 2,5 and a second set of.

[0073] The source 87, 90, 91 are controlled by the computer system 92.

[0074] Referring also to FIG. 8, the operation of the system 31 will be described in more detail.

[0075] A first ion 721 and a second ion 722 are trapped near each other in the microfabricated ion trap 73. The ions 721, 722 are illuminated by a laser beam 88 to serve as a gradient source.

[0076] An oscillating electric field is applied to trap electrodes 84 1,2 , 84 1,4 , 84 2,2 , 84 2,4are input into opposite pairs. By controlling the phase and amplitude of the voltages input to different electrodes, the electric field in the first ion 721 can be made ineffective while generating a desired field in the second ion 722. This enables the application of a single qubit rotation to the right ion without affecting the left ion.

[0077] Control using frequency, phase, and amplitude The methods described herein enable local but parallelizable control in two ways. First, the range or region of a quantum gate can be locally adjusted by setting the amplitude e i and / or the time t i . Second, the phase of a quantum gate can be locally adjusted by setting the phase k i .

[0078] The transition frequency f i for the i-th qubit is known (e.g., determined by simulation) or can be measured. The frequency f G of the oscillation of the gradient field and the frequency f Ei of the oscillation of the local oscillation field can be adjusted for a desired operation at a desired speed.

[0079] Computational and experimental data show that, with other parameters fixed, the single qubit coupling speed is proportional to 1 / (f Mi 2 - f Ei 2 ), where f Mi is the motional frequency of ion i. Thus, a setting f Mi close to f Ei increases the speed of operation by increasing the efficiency of coupling.

[0080] The method enables the implementation of both "spin flip" and "phase flip" quantum operations. The choice of operation depends on the frequency f G of the oscillation of the gradient field and the frequency f Eidepends on the selection. For example, the "spin flip" operation is set to f Ei =f i ±f G (Examples of values are f i = 300 MHz, f G = 6 MHz, f Ei = 306 MHz) and can be executed, and the "phase flip" quantum operation is f Ei =f G and can be executed.

[0081] Resonance operations can be implemented using a combination of a potential gradient and an oscillating electric field, or a combination of a potential gradient, a carrier drive, and an oscillating electric field. The carrier drive can be generated by (a) an electric field generated by one or more laser beams, or (b) a magnetic field. The potential gradient can be generated by (a) one or more laser beams, or (b) a magnetic field gradient using one or more sources.

[0082] The first and second methods of implementing the operation can be implemented using a combination of a potential gradient and an oscillating electric field. The third and fourth methods of implementing the operation use a combination of a potential gradient, a carrier drive, and an oscillating electric field, which will be described later in this specification.

[0083] First Method - Spin Flip The qubit has a transition frequency f i For the oscillating potential gradient at frequency F G and the oscillating electric field at frequency f Ei the "spin flip" operation can be generated using resonance. f G =f i ±f Ei (1) The spin flip speed Ω spin-flip is given by the following equation.

Equation

Number

Number

Number

[0084] The Second Method - Phase Flip The qubit has a transition frequency f i . For the oscillating potential gradient at frequency F G and the oscillating electric field at frequency f Ei , the "phase flip" operation can be generated using resonance. f G = f Ei (5)

[0085] The Third and Fourth Methods - Spin Flip Sometimes a spin flip is desired, but the first method cannot be used because it relies on using a high-frequency potential gradient.

[0086] In the third and fourth methods, an additional oscillating field, for example in the form of an oscillating magnetic field or an oscillating electric field at a frequency f Bi is applied in addition to the oscillating potential gradient at the frequency f G and the oscillating electric field at the frequency f Ei .

[0087] The additional carrier drive can be applied in many different ways, including (a) a magnetic field generated using the same current electrodes used to generate the potential gradient, (b) a magnetic field generated using different electrodes, (c) a magnetic field generated using a remote source such as a microwave horn, (d) a laser field applied from an external laser beam, or a laser field applied through a trap-integrated waveguide.

[0088] Thus, in the third method, the qubit has a transition frequency f G for the oscillating gradient field at the frequency f i , has an oscillating electric field at the frequency f Ei , has an oscillating magnetic field or an oscillating electric field at the frequency f Bi , and "spin flips" can be generated using resonance. f Bi -f i =m(f E -f G ) (6) where m is an integer. Thus, there are many resonances that can each be used to generate spin flips.

[0089] The fourth method is an extension of the second method. All phase flip operations correspond to qubit frequency shifts. Thus, when f G =f Ei , the qubit frequency is shifted from f i to f i +d f , where d f is the oscillating electric field frequency f Ei , the ion motion mode frequency f Mi , the oscillating voltage V i , the oscillating current Ig The phase difference k between the vibration voltage and the current i and the qubit frequency shift that depends on the trap shape, which can be measured by qubit spectroscopy.

[0090] The shift offset d f Once calculated and / or measured, f Bi = f i ± d f The carrier drive with can be applied to generate a spin flip. Overall, the resonance condition is f G = f Ei (7-1) f Bi - f i = d f (7-2) where d f is the qubit frequency shift brought about by applying f G = f Ei .

[0091] The amplitude e i the time t i and the phase k i Changing The following can help understand the effects of adjusting the amplitudes e N of the locally applied electric fields 141, 142,... 14 i the duration t i and the phase k i (FIG. 2) in the aforementioned first and second methods.

[0092] See H. Haffner, C. Roos, and R. Blatt, "Quantum computing with trapped ions": https: / / arxiv.org / pdf / 0809.4368.pdf (2008).

[0093] The operation can be considered with respect to a single qubit quantum gate corresponding to rotation in the Bloch state. Rotation around the z-axis is a phase flip, while rotation around the other axes (i.e., the x-axis or y-axis) is a spin flip.

[0094] The spin flip rotation can be represented in terms of the rotation operator R(θ,φ) (see Equation 10 in the book by H. Haffner, C. Roos, and R. Blatt), where θ controls the rotation angle and can be regarded as the gate area, while φ adjusts the rotation axis and can be regarded as the gate phase. The phase flip rotation can be written as the rotation operator R z (θ).

[0095] In the first method, the rotation to be performed is R(θ,φ). The amplitude e N and period t i of each applied electric field 141, 142, …, 14 i can be changed to adjust θ, while the phase k N of each applied electric field 141, 142, …, 14 i can be changed to adjust φ. In the second method, the rotation to be performed is R z (θ). θ is adjusted by changing the amplitude e i , period t i , and phase k i .

[0096] Additional Explanation The aforementioned method is most effective when the electric field oscillation frequency f Ei is near resonance with the motion frequency f Mi of the ion to which the field is applied. The operation is possible for any electric field oscillation frequency f Ei , but the operating speed increases or decreases depending on the method (resonance) as 1 / (f Mi - f Ei ) or 1 / (f Mi 2 - f Ei 2 ).

[0097] The above method Ei adjusts f Mi near f, so that the voltage V i can be made very low and may have other advantages over methods involving ion transport.

[0098] Improvements It is understood that various improvements can be made to the above-described embodiments. Such improvements are already known in the design, manufacture, and use of trapped ion gates and their components, and can involve equivalent other features that can be used as alternatives or additions to the features already described herein. The features of one embodiment can be replaced or supplemented by the features of other embodiments.

[0099] Although the claims are devised for specific combinations of features in this application, the scope of the disclosure of the present invention includes any novel feature, or any novel combination of features disclosed herein either explicitly or implicitly, or generalizations thereof, whether or not it relates to the same invention currently claimed in any claim, and whether or not it alleviates any or all of the same technical problems as the present invention. Thereby, the applicant hereby notifies that during the prosecution of this application, or during the prosecution of any further applications derived from this application, novel claims may be devised for such features and / or such combinations of features.

Explanation of Reference Numerals

[0100] 11, 12, 1 N Charged particles, ions 21, 22, 2 N Quantum bits 3 Ion trap 41, 42, 4 N Position 5, 6 States 7 Transition 8 System 9 Potential Gradient Generator 11 Potential Gradient, Magnetic Field Gradient, Laser Field 121, 122, 12 N Electrode 131, 132, 13 N Generation Source 141, 142, 14 N Oscillating Electric Field 31 First System 32 Trapped Charged Particles 321, 322 Trapped Ions 33 Charged Particle Trap 34 Control System 35 Quantum Bit 36 Position 37, 38 States 39 Transition 40 Substrate 41 Upper Surface 42 Central Electrode 431 First RF Electrode 432 Second RF Electrode 44, 44 1,1 , 44 1,2 , 44 1,3 , 44 1,4 , 44 1,5 , 44 1,6 , 44 2,1 , 44 2,2 , 44 2,3 , 44 2,4 , 44 2,5 , 44 2,6 Trap Electrode 46 Current Generation Source 47 First End 48 Second End 50 Magnetic Field 51 Magnetic Field Gradient, Potential Gradient 521 First Voltage Generation Source 522 Second Voltage Generation Source 53 1,1 , 53 1,2 , 53 1,3 , 53 1,4 , 53 1,5 , 53 1,6 , 53 2,1 , 53 2,2 , 53 2,3 , 532,4 , 53 2,5 , 53 2,6 Voltage source 54 Computer system 55 Signal generation mechanism 56 DC voltage source 57 Digital - analog converter 58 Amplifier 59 Low - pass RC filter 60 Node 61 AC voltage source 62 AC source 63 Amplifier 64 Series filter 71 Second system 72 Trapped charged particles 721 First ion 722 Second ion 73 Charged particle trap 74 Control system 75 Quantum bit 76 Position 77, 78 States 79 Transition 80 Substrate 81 Upper surface 82 Slot 831, 832 Electrode layer stack 841, 842, 84 1,1 , 84 1,2 , 84 1,3 , 84 1,4 , 84 1,5 , 84 2,1 , 84 2,2 , 84 2,3 , 84 2,4 , 84 2,5 Lower electrode 851, 852 Dielectric layer 86, 861, 862, 86 1,1 , 86 1,2 , 86 1,3 , 86 1,4 , 86 1,5 , 86 2,1 , 86 2,2 , 86 2,3 , 86 2,4 , 86 2,5 Upper electrode 87 Laser 88 Laser beam 89 Electric field gradient 90, 90 1,1 , 90 1,2 , 90 1,3 , 90 1,4 , 90 1,5 , 90 2,1 , 90 2,2 , 90 2,3 , 90 2,4 , 90 2,5 The first set of voltage sources 91, 91 1,1 , 91 1,2 , 91 1,3 , 91 1,4 , 91 1,5 , 91 2,1 , 91 2,2 , 91 2,3 , 91 2,4 , 91 2,5 The second set of voltage sources 92 Computer system C Capacitor f Ei The frequency of the electric field f i Transition frequency e i The amplitude of the electric field k i The phase of the electric field f1, f2, f N Transition frequency f G The frequency of vibration f i Transition frequency g1, g2, g N The magnitude of the potential gradient 11 I(t) Oscillating current R Resistance t i Time

Claims

1. A method of operating a charged particle trap including a set of trap electrodes, comprising: trapping a first charged particle having a first qubit with a first transition frequency at a first position; trapping a second charged particle having a second qubit with a second transition frequency at a second position; applying a potential gradient to the first charged particle and the second charged particle, wherein the first charged particle receives a first potential gradient magnitude and the second charged particle receives a second potential gradient magnitude, and the potential gradient oscillates at a given frequency and is monochromatic; including while applying the potential gradient, applying a first oscillating potential to a first electrode at a first frequency so as to apply a first oscillating electric field to the first charged particle; applying a second oscillating potential to a second electrode at a second frequency so as to apply a second oscillating electric field to the second charged particle including.

2. The method according to claim 1, wherein the first oscillating electric field has a first phase value and / or the second oscillating electric field has a second different phase value.

3. The step of applying the potential gradient includes applying at least one magnetic field gradient to the first charged particle and the second charged particle at the given frequency, applying a laser field to the first charged particle and the second charged particle at the given frequency, and / or applying a first laser field and a second laser field to the first charged particle and the second charged particle, the first laser field and the second laser field having a first laser frequency and a second laser frequency respectively, and the difference between the first laser frequency and the second laser frequency being equal to the given frequency. The method according to claim 1 or 2, including

4. The method according to any one of claims 1 to 3, further including applying carrier drive to the first charged particle and the second charged particle.

5. The step of applying the potential gradient includes driving an oscillating current through an elongated conductive element to generate the at least one magnetic field. The method according to claim 3 or 4.

6. The method according to claim 5, wherein the elongated conductive element includes a first region and a second region, and the first region and the second region of the elongated conductive element are not collinear.

7. The step of applying the at least one potential gradient to the first charged particle and the second charged particle comprises: driving a first oscillating current through a first elongated conductive element; driving a second oscillating current through a second elongated conductive element spaced apart from the first elongated conductive element The method according to claim 3 or 4, comprising:

8. The method according to any one of claims 1 to 7, wherein the charged particle trap comprises a substrate having a main surface, and at least a first set of the set of trap electrodes is disposed on the main surface of the substrate.

9. The method according to claim 8, wherein a second set of the set of trap electrodes is supported on a different surface and is not in the same plane as the first set.

10. The method according to claim 8 or 9, wherein the charged particle trap comprises at least one elongated conductive element for generating the at least one magnetic field.

11. The method according to claim 10, wherein the set of trap electrodes includes a first array and a second array of trap electrodes, and the at least one elongated conductive element is interposed between the first array and the second array of trap electrodes.

12. The method according to claim 10, wherein the one elongated conductive element is supported on a different surface and is not in the same plane as the first set of trap electrodes.

13. The step of applying the potential gradient to the first charged particle and the second charged particle comprises: The method according to any one of claims 1 to 12, comprising illuminating the first charged particle and the second charged particle with at least one laser beam.

14. The first charged particle has a given oscillation mode having a given oscillation direction, and the method comprises: applying the potential gradient such that the potential gradient in the first charged particle has a component not perpendicular to the given oscillation direction and the potential gradient in the second charged particle has a component not perpendicular to the given oscillation direction. applying the first oscillating electric field such that the first oscillating electric field is not perpendicular to the given oscillation direction; applying the second oscillating electric field such that the second oscillating electric field is not perpendicular to the given oscillation direction The method according to any one of claims 1 to 13, comprising:

15. The method according to any one of claims 1 to 14, wherein the set of trap electrodes includes the first electrode and the second electrode.

16. A charged particle trap including a set of trap electrodes; A control system for controlling the charged particle trap; Comprising: The control system is configured to: trap a first charged particle having a first transition frequency at a first position; trap a second charged particle having a second transition frequency at a second position; applying a potential gradient to the first charged particle and the second charged particle, wherein the first charged particle receives a magnitude of a first potential gradient, the second charged particle receives a magnitude of a second potential gradient, and the potential gradient oscillates at a given frequency and is monochromatic; while applying the potential gradient; applying a first oscillating potential at a first frequency to a first electrode so as to apply a first oscillating electric field to the first charged particle; applying a second oscillating potential at a second frequency to a second electrode so as to apply a second oscillating electric field to the second charged particle A system configured to perform.

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