Calculating neVichislimoe
By: Ted Dzen
Tags: Tech, Computer Science, Quantum Computing, Hacking, Technology

Technology and science always evolve as a reaction to growing human needs and interests. Though the world of binary has a firm grasp on current needs and purposes, nothing lasts forever. Such factors like limitations in computing power, computer security, scarce low-level logical flexibility, etc. infuse the demand on modifying currently available architectures or even designing one anew.

Quantum computing

This specific area of R&D is the main subject area of may computer scientists and leading IT companies. The story of love started with quantum computers in 1980 with Paul Benioff. Benioff showed that a computer could operate under the laws of quantum mechanics by describing a Schrödinger equation description of a Turing machine. After more than 25 years of continuous research, quantum computing got ist current identity and political weight. If you wish to know why conventional

The scientific field of quantum computing is wide. It seeks to solve different complex problems in such areas as cryptography, computing algorithms, telecommunications, cybersecurity and more. More than 70 companies are researching and developing products in this sphere. For instance, IBM, Google, NLC, etc.

Quantum computing is going to be described below in terms of different architectural designs, required hardware, and software components

Difference between existing quantum computing architectures

What has to be said is that the core of the QC operation process is quantum chemical reactions. It’s possible to discover that a couple of different front-running technologies exist behind QC. Some of those are superconducting transmon qubits and trapped-ion qubits, with other candidate technologies also of considerable interest. The different methods of forming qubits are sufficiently different even to such extent that fundamental gate operations performed on them differ widely. Other than that inter-qubit interaction methods differ enormously what leds to widely disparate communication approaches and connectivity topologies.

If you are interested in more extended information on comparison of quantum architectures , refer to:

https://arxiv.org/pdf/1905.11349.pdf

Hardware

Like conventional computers, those based on quantum mechanics ought to have hardware components. In order or conceptualize the necessary hardware components for an analog or gate-based QC, abstract notions are to be injected: quantum data plane, control and measurement plane, control processor plane, host processor.

The quantum data plane is the main engine or QC. Its destiny is to underpin the operations with q-bits, including holding them in place, measure the qubits’ state and perform gate operations on the physical qubits for a gate-based system or control the Hamiltonian for an analog computer. There are some operational rules of QC, which differentiates it from classical silicon computers. Only two or more q-bit can interact with each other using correct networking wires, otherwise, q-bits fidelity metrics plummet. Thus the most important metrics at this layer are q-bit fidelity and connectivity.

The control plane and data plane can’t be based on the same quantum architecture, unlike in conventional computers. Usually, a control plane transmits control signals via electric wire, light or microwave radiation — it depends on the underlying qubit technology. Systems using trapped-ion qubits usually use microwave and optical signals transmitted through waveguides, whereas superconducting qubit systems rely on microwave and low-frequency signals which reach their destination using cryostats. The aspect that challenges scientists to the greatest extent is the fact that controls have to be sent directly to q-bits themselves, what becomes an issue when the number of q-bit grows. Signal crosswalk and quality of generated signal itself also directly impacts qubit operations. Mechanism for error correction and calibration is required.

( In some way quantum data plane is similar to a Field programmable gate array, which can be configured in run time to perform a specific task)

The process of running a program on QC is a bit different from that on a classical computer. On top of a control plane , lies control processor plane, which is split in two parts: classical processor for running q-programs and scalable custom hardware block which works as a call-bridge between higher layers and control/measurement plane. The control processor plane identifies and triggers the proper Hamiltonian or sequence of quantum gate operations and measurements. Thereby triggering a program execution. Basically it is a compiler. A user on its side always interacts with host processor, which is a conventional computer, having required software and libraries to work with a control processor plane.

Software and quantum programming

Same as in classical computers, over newcomer QC must have a way to be programmed. It’s crucial for enabling its design and use. Combination of compilers and languages, that we are going to call toolchains,are designed and used with the goal of saving qubit and time of program execution. The development of programming language for QCs is a nontrivial task. High-level quantum programming language should strike a balance between abstraction and detail.

Similar to conventional computers QCs have their own assembly language called QASM. Currently, some convergence is being seen on the OpenQASM quantum assembly-level language, which combines elements of assembly languages and C with the original QASM constructs. In the final phases of compilation, a program represented in a QIR like OpenQASM is translated into appropriate control instructions, producing code for the control processor. The control processor drives signals to the control and measurement plane.

From a standpoint of conventional programer software libraries is a convenient method of making programming process faster and more pleasant. That’s why basic algorithms is to be realized out of the box. Addition, multiplication, some more complex algorithms like modular arithmetic, implementation of block ciphers, and hash functions etc. This shields algorithm-level programmers from the burden of fully familiarizing themselves with hardware details while optimizing for circuit width or depth.

Generic tool flow for quantum programming. A quantum program is implemented in a domain-specific language (DSL) and then translated into hardware instructions after undergoing a series of compiler transformations and optimizations. A quantum intermediate representation (QIR) of the program can serve as a logical-level analog to conventional assembly code. For programs running on error-corrected qubits, the compiler would link in low-level QEC libraries into the code, transforming the logical qubit operations, to the physical operations on a number of qubits. The qubits of this “expanded” quantum program are then mapped onto a specific hardware implementation accounting for the specific gate operations and connectivity available.

The next step to reach the goal of executing the program is a gate synthesis. Arbitrary single-qubit rotations cannot be expressed exactly using a Clifford + T gate set; thus, these rotations must be decomposed a series of gate operations. Decomposition enables a general circuit expressed in arbitrary unitaries. The most used universal gate set is Clifford + T gate set; however, other gates are also possible (Clifford and Toffoli, V basis gate set, etc.).

Usefull tools:

https://github.com/qosf/awesome-quantum-software

Era of quantum security?

Quantum cybersecurity is the field that studies all aspects affecting the security and privacy of communications and computations caused by the development of quantum technologies.

The security of encryption is quantified in terms of “bits of security.” This provides an easy way to compare algorithms with different properties. It takes about 2,128 computational steps for an attacker to crack a 128-bit AES key, a 256-bit elliptic curve key, or a 3,072-bit RSA key. We say that each of these approaches to encryption provides 128 bits of security.

But the number of steps that it takes to crack a key depends on the computer you use. The fact that a 3,072-bit RSA key provides 128 bits of security assumes that an attacker is using a classical computer, not a quantum one.

The nature of quantum computers — computers that use qubits instead of just traditional bits — makes it possible to implement algorithms that cannot be implemented on classical computers, and these dramatically affect the security of some encryption algorithms. In particular, there is an algorithm that runs on a quantum computer that reduces the security of a 3,072-bit RSA key down to only about 26 bits. It is essentially impossible with the non-quantum technology that will be available in the foreseeable future to crack a key that provides 128 bits of security, but you can easily crack one that provides only 26 bits of security with the computing power of a cellphone.

No need to be worried. Post-quantum cryptography is to safe us from newly generated traffic and data to be decrypted(only if you install SSL cert generated with post-q crypto algorithm). However, when large fault-tolerant q-computers will be constructed, mostly used crypto-systems will brake suddenly, what mostly will stay undercover for some time. Who knows why NSA collects all current ongoing TLS encrypted traffic featured with traffic perfect forward secrecy , flowing through US Internet backbone nodes…

Prospects of QC market development

While much progress has been made in the development of small-scale quantum computers, the quantum computer system that can scale to the size needed to break current cryptography has not been demonstrated, nor can it be achieved by straightforward scaling of any of the current implementations.

Quantum computers with 50–100 qubits may be able to perform tasks which surpass the capabilities of today’s classical digital computers, but noise in quantum gates will limit the size of quantum circuits that can be executed reliably. However, there are a couple of low-noise solutions for building quantum gates based on superconducting metals and diamonds. Scientists believe that these can enable manufacturers to build portable QCs, however, it is still a state of art technology.

As a result, it is not clear whether the current leading quantum technologies will be used to create this class of analog high-performance machines. Maybe some others can?