Systems and methods of optical restoration include, with a photonic service (14), in an optical network (10, 100), operating between two nodes (A, Z) via an associated optical modem (40) at each node, wherein each modem (40) is capable of supporting variable capacity, C.sub.1, C.sub.2, . . . , C.sub.N where C.sub.1>C.sub.2> . . . >C.sub.N, detecting a fault (16) on a home route of the photonic service (14) while the photonic service (14) operates at a home route capacity C.sub.H, C.sub.H is one of C.sub.1, C.sub.2, . . . , C.sub.N−1; downshifting the photonic service (14) to a restoration route capacity C.sub.R, C.sub.R is one of C.sub.2, C.sub.3 . . . , C.sub.N and C.sub.R<C.sub.H; switching the photonic service (14) from the home route to a restoration route (18) while the photonic service (14) operates at a restoration route capacity C.sub.R; and monitoring the photonic service (14) and copropagating photonic services during operation on the restoration route (18) at the restoration route capacity C.sub.R for an upshift of the photonic service (14).

An apparatus useful for creating and measuring states of an entangled system, comprising a pair of interacting multi-level systems, each of systems comprising a state |g>; a state |r>, and state |r*>. One or more first electromagnetic fields excite a first transition between the ground state |g> and the state |r> to create an entangled system. One or more second electromagnetic fields are tuned between the state |r> and the intermediate state |r*> so that any population of the systems in |r*> are dark to a subsequent detection of a population in the systems in |g>, providing a means to distinguish the entangled system in the state |g> and the entangled system in the state |r>. In one or more examples, the systems comprise neutral Rydberg atoms.

An apparatus useful for creating and measuring states of an entangled system, comprising a pair of interacting multi-level systems, each of systems comprising a state |g>; a state |r>, and state |r*>. One or more first electromagnetic fields excite a first transition between the ground state |g> and the state |r> to create an entangled system. One or more second electromagnetic fields are tuned between the state |r> and the intermediate state |r*> so that any population of the systems in |r*> are dark to a subsequent detection of a population in the systems in |g>, providing a means to distinguish the entangled system in the state |g> and the entangled system in the state |r>. In one or more examples, the systems comprise neutral Rydberg atoms.

Embodiments are disclosed for a quantum key distribution enabled intra-datacenter network. An example system includes a first vertical cavity surface emitting laser (VCSEL), a second VCSEL and a network interface controller. The first VCSEL is configured to emit a first optical signal associated with data. The second VCSEL is configured to emit a second optical signal associated with quantum key distribution (QKD). Furthermore, the network interface controller is configured to manage transmission of the first optical signal associated with the first VCSEL and the second optical signal associated with the second VCSEL via an optical communication channel coupled to a network interface module.

Embodiments are disclosed for a quantum key distribution enabled intra-datacenter network. An example system includes a first vertical cavity surface emitting laser (VCSEL), a second VCSEL and a network interface controller. The first VCSEL is configured to emit a first optical signal associated with data. The second VCSEL is configured to emit a second optical signal associated with quantum key distribution (QKD). Furthermore, the network interface controller is configured to manage transmission of the first optical signal associated with the first VCSEL and the second optical signal associated with the second VCSEL via an optical communication channel coupled to a network interface module.

Systems, apparatuses, methods, and computer program products are disclosed for quantum entanglement authentication (QEA). An example method includes generating, at a first computing device, a first number based on a subset of a first set of entangled quantum particles comprised by a quantum authentication device and associated with the first computing device. Each entangled quantum particle in the first set of entangled quantum particles may be entangled with a respective entangled quantum particle in a second set of entangled quantum particles associated with a second computing device. The example method further includes transmitting an electronic identification of the subset of the first set of entangled quantum particles to the second computing device. In some instances, the example method may further include receiving a second number from the second computing device and authenticating a session between the first computing device and the second computing device in an instance in which the second number corresponds, or is identical, to the first number.

Systems, apparatuses, methods, and computer program products are disclosed for quantum entanglement authentication (QEA). An example method includes generating, at a first computing device, a first number based on a subset of a first set of entangled quantum particles comprised by a quantum authentication device and associated with the first computing device. Each entangled quantum particle in the first set of entangled quantum particles may be entangled with a respective entangled quantum particle in a second set of entangled quantum particles associated with a second computing device. The example method further includes transmitting an electronic identification of the subset of the first set of entangled quantum particles to the second computing device. In some instances, the example method may further include receiving a second number from the second computing device and authenticating a session between the first computing device and the second computing device in an instance in which the second number corresponds, or is identical, to the first number.

Methods and apparatus for piecewise addition into an accumulation register using one or more carry runway registers, where the accumulation register includes a first plurality of qubits with each qubit representing a respective bit of a first binary number and where each carry runway register includes multiple qubits representing a respective binary number. In one aspect, a method includes inserting the one or more carry runway registers into the accumulation register at respective predetermined qubit positions, respectively, of the accumulation register; initializing each qubit of each carry runway register in a plus state; applying one or more subtraction operations to the accumulation register, where each subtraction operation subtracts a state of a respective carry runway register from a corresponding portion of the accumulation register; and adding one or more input binary numbers into the accumulation register using piecewise addition.

Methods and apparatus for piecewise addition into an accumulation register using one or more carry runway registers, where the accumulation register includes a first plurality of qubits with each qubit representing a respective bit of a first binary number and where each carry runway register includes multiple qubits representing a respective binary number. In one aspect, a method includes inserting the one or more carry runway registers into the accumulation register at respective predetermined qubit positions, respectively, of the accumulation register; initializing each qubit of each carry runway register in a plus state; applying one or more subtraction operations to the accumulation register, where each subtraction operation subtracts a state of a respective carry runway register from a corresponding portion of the accumulation register; and adding one or more input binary numbers into the accumulation register using piecewise addition.

A quantum telecommunications network includes nodes, typically on the ground; a conventional telecommunications network connecting the nodes to one another; and at least one satellite or airborne carrier able to generate and transmit multiplets of entangled photons to the nodes. The nodes are configured to collect photons from the satellite, take joint quantum measurements and exchange conventional information with other nodes via the conventional telecommunications network. Node and satellite payload for such a quantum telecommunications network. Method for quantum telecommunications by way of such a network.