A class for date and time repesentation in C++11

I need a Class able to store date and time information in UTC (no timezone/locale required) and I also need to perform basic arithmetic operations on those date/times (addition, subtraction) and comparison. Ideally I would like use the C++11 standard library, if that is possible.

std::chrono seems a good candidate for my purposes. My DateTime class could be as simple as an alias of chrono::time_point with the desired precision. e.g.

using UTCTime = std::chrono::time_point<SomeClock>;

Defining a custom clock (SomeClock) allows my class to be type safe, whilechrono::time_point class provides the computational requirements.

The missing piece of the puzzle are the functions to convert to/from date and time information. chrono::system_clock offers the methods to_time_t and from_time_t, which are limited by the precision of seconds, which is not good enough for me.

Does anybody have a solution for that?