A modular quantum computer architecture is developed with a hierarchy of interactions that can scale to very large numbers of qubits. Local entangling quantum gates between qubit memories within a single modular register are accomplished using natural interactions between the qubits, and entanglement between separate modular registers is completed via a probabilistic photonic interface between qubits in different registers, even over large distances. This architecture is suitable for the implementation of complex quantum circuits utilizing the flexible connectivity provided by a reconfigurable photonic interconnect network. The subject architecture is made fault-tolerant which is a prerequisite for scalability. An optimal quantum control of multimode couplings between qubits is accomplished via individual addressing the qubits with segmented optical pulses to suppress crosstalk in each register, thus enabling high-fidelity gates that can be scaled to larger qubit registers for quantum computation and simulation.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A quantum computer comprising: a processor; a plurality of modular elementary logic units (ELUs), each ELU including a plurality of qubits, the plurality of qubits including ion qubits; a photonic interconnect network operatively coupled to the plurality of ELUs and configured for multiplexing under control of the processor; a control sub-system configured to control qubit-state-dependent forces; a photon detection sub-system operatively coupled to a first and second quantum gates via the photonic interconnect network; a measurement sub-system operatively coupled to the detection sub-system and the first and second quantum gates; and the ion qubits including a laser sub-system having a first laser configured to initialize each ion qubits in a respective ELU; a second continuous wave laser configured to stimulate Raman transitions between the ion qubits; and a third resonant laser configured to participate in ion qubits state measurement. 2. The quantum computer of claim 1, wherein a pulse shape of a beam emitted from the second laser is evenly partitioned into (2Nq+1) segments wherein Nq is the number the ion qubits in the respective ELU. 3. The quantum computer of claim 2, configured according to a set of control parameters that include a predetermined addressing of the ion qubits, and a spectral phase and an amplitude of a beam emitted from the second laser. 4. The quantum computer of claim 1, further comprising at least one multi-dimensional quantum computational structure having a fault-tolerant probabilistic connection between respective distant modular ELUs. 5. The quantum computer of claim 4, wherein the respective ELU is provided with a plurality of communication ports coupled to the photonic interconnect network, and further comprising a time division multiplexing (TDM) mechanism applied to said communication ports. 6. The quantum computer of claim 5, further comprising a fault-tolerance sub-system operatively coupled to at least one of first and second quantum gates. 7. The quantum computer of claim 1, further comprising at least one multi-dimensional quantum computational structure configured as a multi-dimensional hypercell of multiplexed modular ELUs. 8. The quantum computer of claim 7, wherein the hypercell includes: a snowflake contoured connectivity tree having ELUs positioned at a respective node of the snowflake's connectivity tree; wherein the ELUs in said connectivity tree are interconnected to form a root ELU, and multiple layers of ELU branches are coupled to the root ELU, thereby forming an extended surface area with a number of external ELU's communication ports; wherein at least two of the snowflake hypercells are entangled at said surface areas thereof via said external communication ports thereby attaining a photons link therebetween; and wherein a Bell pair created between said at least two hypercells is teleported to a Bell pair between the root ELUs of said hypercells. 9. The quantum computer of claim 7, wherein the ELUs are linked through the photonic interconnect network into at least one three-dimensional (3D) hypercell. 10. The quantum computer of claim 1, wherein at least one ELU includes at least one chain of physical qubits, refrigerator qubits interposed between quantum gates, and communication qubits coupled to the photonic interconnect network. 11. The quantum computer of claim 10, wherein the refrigerator qubits exhibit a different species than the physical qubits. 12. The quantum computer of claim 10, further comprising an isolating mechanism for isolating the communication qubits from the physical qubits. 13. The quantum computer of claim 1, wherein the photon detection sub-system includes an array of NELU/2 Bell state detectors. 14. The quantum computer of claim 1, wherein the processor is configured to apply entanglement swapping protocols to coordinate entanglement generation time with communication times. 15. The quantum computer of claim 1, including a quantum adder circuit configured to compute a sum of two n-bit integers and employing 6n logical qubits placed on 1.5n ELUs to compute said sum of two n-bit integers at a first concatenation level of Steane code encoding.